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When water vapor comes into contact with a cold surface, it condenses into water droplets. This natural phenomenon is called breath figures (BFs). Interestingly, ordered BFs can be formed on a volatile liquid surface. Different volatile liquids can induce different BFs, but the growth process of ordered BFs is not fully understood. Although it is believed that BFs can form on the surface of a volatile liquid, such as dichloromethane, there is little experimental evidence to support this claim. Herein, the growth of BFs on a surface of pure dichloromethane without any polymer was observed in situ by an optical microscope (OM) in a static humid environment. The OM images were analyzed to obtain details, and the ordered breath figure arrays (BFAs) were observed on the volatile liquid surface. It is found that there are three distinct power-law growth exponents, and the growth of BFs followed a single droplet growth before coalescing. Moreover, it was observed that water droplets were rapidly moving throughout the water droplet growth. The growth dynamics of BFs on the volatile surface of pure dichloromethane have unique characteristics, which are different from the reported results on nonvolatile surfaces, volatile solutions with polymer, and pure carbon disulfide. These results provide direct evidence for ordered BFs from pure dichloromethane and help explain the mechanism of ordered BFs on volatile liquid surfaces. [ABSTRACT FROM AUTHOR]

We have observed details of the internal motion and dissociation channels in photoexcited carbon disulfide (CS2) using time-resolved x-ray scattering (TRXS). Photoexcitation of gas-phase CS2 with a 200 nm laser pulse launches oscillatory bending and stretching motion, leading to dissociation of atomic sulfur in under a picosecond. During the first 300 fs following excitation, we observe significant changes in the vibrational frequency as well as some dissociation of the C–S bond, leading to atomic sulfur in the both 1D and 3P states. Beyond 1400 fs, the dissociation is consistent with primarily 3P atomic sulfur dissociation. This channel-resolved measurement of the dissociation time is based on our analysis of the time-windowed dissociation radial velocity distribution, which is measured using the temporal Fourier transform of the TRXS data aided by a Hough transform that extracts the slopes of linear features in an image. The relative strength of the two dissociation channels reflects both their branching ratio and differences in the spread of their dissociation times. Measuring the time-resolved dissociation radial velocity distribution aids the resolution of discrepancies between models for dissociation proposed by prior photoelectron spectroscopy work. [ABSTRACT FROM AUTHOR]

Transition energies and generalized oscillator strengths (GOSs) for transitions up to 6.3 eV of carbon disulfide were calculated at the multireference configuration interaction level. It is shown that the consideration of the vibronic coupling mechanism is essential to establish not only a quantitative but also a qualitative profile of the GOS, as a function of the momentum transferred, for the dipole forbidden transitions ( Σ g + 1 → 1 Σ u − and Σ g + 1 → 1 Δ u ). For the dipole allowed Σ g + → Σ u + transition, the calculated GOS is in good agreement with the available experimental data. [ABSTRACT FROM AUTHOR]

We report observation of new infrared bands of (CS2)2 and (CS2)3 in the region of the CS2 ν1 + ν3 combination band (at 4.5 µm) using a quantum cascade laser. The complexes are formed in a pulsed supersonic slit-jet expansion of a gas mixture of carbon disulfide in helium. We have previously shown that the most stable isomer of (CS2)2 is a cross-shaped structure with D2d symmetry and that for (CS2)3 is a barrel-shaped structure with D3 symmetry. The dimer has one doubly degenerate infrared-active band in the ν1 + ν3 region of the CS2 monomer. This band is observed to have a rather small vibrational shift of −0.844 cm−1. We expect one parallel and one perpendicular infrared-active band for the trimer but observe two parallel bands and one perpendicular band. Much larger vibrational shifts of −8.953 cm−1 for the perpendicular band and −8.845 cm−1 and +16.681 cm−1 for the parallel bands are observed. Vibrational shifts and possible vibrational assignments, in the case of the parallel bands of the trimer, are discussed using group theoretical arguments. [ABSTRACT FROM AUTHOR]

Ground-state rotational spectra were observed for ten symmetric-top isotopologues H3N⋯S=C=S, H3N⋯34S=C=S, H3N⋯S=C=34S, H3N⋯S=13C=S, H315N⋯S=C=S, H315N⋯34S=C=S, H315N⋯S=C=34S, H315N⋯S=13C=S, H315N⋯33S=C=S, and H315N⋯S=C=33S, the first five in their natural abundance in a mixture of ammonia and carbon disulphide in argon and the second group with enriched 15NH3. The four asymmetric-rotor isotopomers H2DN⋯S=C=S, H2DN⋯34S=C=S, H2DN⋯S=C=34S, and HD2N⋯S=C=S were investigated by using a sample composed of ND3 mixed with CS2. Rotational constants, centrifugal distortion constants, and 33S nuclear quadrupole coupling constants were determined from spectral analyses and were interpreted with the aid of models of the complex to determine its symmetry, geometry, one measure of the strength of the intermolecular binding, and information about the subunit dynamics. The complex has C3v symmetry, with nuclei in the order H3N⋯S=C=S, thereby establishing that the non-covalent interaction is a chalcogen bond involving the non-bonding electron pair of ammonia as the nucleophile and the axial region near one of the S atoms as the electrophile. The small intermolecular stretching force constant kσ = 3.95(5) N m−1 indicates a weak interaction and suggests the assumption of unperturbed component geometries on complex formation. A simple model used to account for the contribution of the subunit angular oscillations to the zero-point motion leads to the intermolecular bond length r(N⋯S) = 3.338(10) Å. [ABSTRACT FROM AUTHOR]

Carbon disulfide is a prototype molecular system for studies of photophysical processes in molecules at different time scales and is also relevant to astrophysics. Here, reliable molecular properties are computed for linear SCS, bent cyc-CS2, and linear CSS forms using highly correlated post Hartree-Fock methods in conjunction with large basis sets. Structures are identified using explicitly correlated and standard coupled cluster techniques. Evolution of the lowest-lying singlet and triplet electronic states of the three isomers along the SS and CS stretching coordinates and along the bending angle are mapped at the multireference configuration interaction (MRCI)/aug-cc-pV(5+d)Z level of theory. The computations suggest that the 1B2(1Σ+) electronic state of the SCS isomer plays an important role in the photoconversion of CS2 to cyc-CS2 and CSS. Photoconversion competes with photodissociation. Plausible mechanisms for the production of S2 and CS diatomics after the photoexcitation of SCS are proposed. To aid in the identification of CSS in the laboratory and in astrophysical media, a set of spectroscopic constants and rovibrational levels for CSS are reported. [ABSTRACT FROM AUTHOR]

Carbon disulfide is a prototype molecular system for studies of photophysical processes in molecules at different time scales and is also relevant to astrophysics. Here, reliable molecular properties are computed for linear SCS, bent cyc-CS2, and linear CSS forms using highly correlated post Hartree-Fock methods in conjunction with large basis sets. Structures are identified using explicitly correlated and standard coupled cluster techniques. Evolution of the lowest-lying singlet and triplet electronic states of the three isomers along the SS and CS stretching coordinates and along the bending angle are mapped at the multireference configuration interaction (MRCI)/aug-cc-pV(5+d)Z level of theory. The computations suggest that the 1B2(1Σ+) electronic state of the SCS isomer plays an important role in the photoconversion of CS2 to cyc-CS2 and CSS. Photoconversion competes with photodissociation. Plausible mechanisms for the production of S2 and CS diatomics after the photoexcitation of SCS are proposed. To aid in the identification of CSS in the laboratory and in astrophysical media, a set of spectroscopic constants and rovibrational levels for CSS are reported. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulation studies were performed to investigate the structural and dynamic properties of liquid carbon disulfide (CS2) from ambient to elevated pressure conditions. The results obtained have revealed structural changes at high pressures, which are related to the more dense packing of the molecules inside the first solvation shell. The calculated neutron and X-ray structure factors have been compared with available experimental diffraction data, also revealing the pressure effects on the short-range structure of the liquid. The pressure effects on the translational, reorientational, and residence dynamics are very strong, revealing a significant slowing down when going from ambient pressure to 1.2 GPa. The translational dynamics of the linear CS2 molecules have been found to be more anisotropic at elevated pressures, where cage effects and librational motions are reflected on the shape of the calculated time correlation functions and their corresponding spectral densities. [ABSTRACT FROM AUTHOR]

We used transient visible/near-infrared absorption spectroscopy and ultrafast dynamic ellipsometry to characterize carbon disulfide (CS2) shocked with an ultrafast laser pulse. We found a volumedecreasing reaction, characterized by the deviation of the shock and particle velocity (us and up) points from the unreacted Hugoniot, above up=1.5 km/s. This result contrasts with literature plateimpact data, which found the reaction-induced deviation from the unreacted Hugoniot to occur at up=1.2 km/s. We attribute this disparity to the difference in timescale between plate-impact experiments (ns to μs) and our ultrafast experiments (sub-ns), as our ultrafast experiments require higher shock pressures and temperatures for an observable reaction. The volume-decreasing reaction was accompanied by a large increase in absorption of the reaction products, necessitating the use of impedance matching techniques to characterize the us-up points above the reaction cusp. Using transient absorption spectroscopy, we discovered a change in the absorption spectrum for shock strengths below and above the volume-decreasing reaction, suggesting there are multiple chemical reactions in CS2 shocked to above 7.4 GPa in 300 ps. [ABSTRACT FROM AUTHOR]

Theoretical studies of the potential energy surfaces (PESs) and bound states are performed for rare gas-carbon disulfide complexes, He-CS2, Ne-CS2, and Ar-CS2. Three two-dimensional intermolecular PESs are constructed from ab initio data points which are calculated at the CCSD(T) level with aug-cc-pVTZ basis set supplemented with bond functions. We find that the three PESs have very similar features and each PES can be characterized by a global T-shaped minimum, two equivalent local linear minima, and the saddle points between them. The T-shaped isomer is energetically more stable than the linear isomer for each complex. The linear isomers, which have not been observed in experiment so far, are predicted from our PESs and further identified by bound state calculations. Moreover, we assign several intermolecular vibrational states for both the T-shaped and linear isomers of the three complexes via the analysis of wave functions. The corresponding vibrational frequencies are calculated from the bound state energies for these assigned states. These frequencies could be helpful for further experimental studies, especially for the linear isomers. We also calculate the rovibrational transition frequencies for the three T-shaped isomers and the pure rotational transition frequencies for the linear isomers, respectively. The accuracy of the PESs is validated by the good agreement between theoretical and experimental results for the rovibrational transition frequencies and spectroscopic parameters. [ABSTRACT FROM AUTHOR]

Theoretical studies of the potential energy surfaces (PESs) and bound states are performed for rare gas-carbon disulfide complexes, He-CS2, Ne-CS2, and Ar-CS2. Three two-dimensional intermolecular PESs are constructed from ab initio data points which are calculated at the CCSD(T) level with aug-cc-pVTZ basis set supplemented with bond functions. We find that the three PESs have very similar features and each PES can be characterized by a global T-shaped minimum, two equivalent local linear minima, and the saddle points between them. The T-shaped isomer is energetically more stable than the linear isomer for each complex. The linear isomers, which have not been observed in experiment so far, are predicted from our PESs and further identified by bound state calculations. Moreover, we assign several intermolecular vibrational states for both the T-shaped and linear isomers of the three complexes via the analysis of wave functions. The corresponding vibrational frequencies are calculated from the bound state energies for these assigned states. These frequencies could be helpful for further experimental studies, especially for the linear isomers. We also calculate the rovibrational transition frequencies for the three T-shaped isomers and the pure rotational transition frequencies for the linear isomers, respectively. The accuracy of the PESs is validated by the good agreement between theoretical and experimental results for the rovibrational transition frequencies and spectroscopic parameters. [ABSTRACT FROM AUTHOR]

We study the photodissociation dynamics of CS2 in the ultraviolet region using the time-sliced velocity map ion imaging technique. The S(3PJ)+CS(X1Σ+) product channels were observed and identified at four wavelengths of 201.36, 203.10, 204.85 and 206.61 nm. In the measured images of S(3PJ=2,1,0), the vibrational states of the CS(X1Σ+) co-products were partially resolved and the vibrational state distributions were determined. Moreover, the product total kinetic energy releases and the anisotropic parameters were derived. The relatively small anisotropic parameter values indicate that the S(3PJ=2,1,0)+CS(X1Σ+) channels are very likely formed via the indirect predissociation process of CS2. The study of the S(3PJ=2,1,0)+CS(X1Σ+) channels, which come from the spin-orbit coupling dissociation process of CS2, shows that nonadiabatic process plays a role in the ultraviolet photodissociation of CS2. [ABSTRACT FROM AUTHOR]

The dense phase of CO2-CS2 mixtures has been analysed by Raman spectroscopy as a function of the CO2 concentration (0.02-0.95 mole fractions) by varying the pressure (0.5 MPa up to 7.7 MPa) at constant temperature (313 K). The polarised and depolarised spectra of the induced (ν2, ν3) modes of CS2 and of the ν1-2ν2 Fermi resonance dyad of both CO2 and CS2 have been measured. Upon dilution with CO2, the evolution of the spectroscopic observables of all these modes displays a 'plateau-like' region in the CO2 mole fraction 0.3-0.7 never previously observed in CO2-organic liquids mixtures. The bandshape and intensity of the induced modes of CS2 are similar to those of pure CS2 up to equimolar concentration, after which variations occur. The preservation of the local ordering from pure CS2 to equimolar concentration together with the non-linear evolution of the spectroscopic observables allows inferring that two solvation regimes exist with a transition occurring in the plateau domain. In the first regime, corresponding to CS2 concentrated mixtures, the liquid phase is segregated with dominant CS2 clusters, whereas, in the second one, CO2 monomers and dimers and CO2-CS2 hetero-dimers coexist dynamically on a picosecond time-scale. It is demonstrated that the subtle interplay between attractive and repulsive interactions which provides a molecular interpretation of the non-ideality of the CO2-CS2 mixture allows rationalizing the volume expansion and the existence of the plateau-like region observed in the pressure-composition diagram previously ascribed to the proximity of an upper critical solution temperature at lower temperatures. [ABSTRACT FROM AUTHOR]

We report absolute differential cross sections (DCSs) for elastic electron scattering from OCS (carbonyl sulphide) and CS2 (carbon disulphide) in the impact energy range of 1.2-200 eV and for scattering angles from 10° to 150°. Above 10 eV, the angular distributions are found to agree quite well with our present calculations using two semi-phenomenological theoretical approaches. One employs the independent-atom model with the screening-corrected additivity rule (IAM-SCAR), while the other uses the continuum-multiple-scattering method in conjunction with a parameter-free exchange-polarization approximation. Since OCS is a polar molecule, further dipole-induced rotational excitation cross sections have been calculated in the framework of the first Born approximation and incoherently added to the IAM-SCAR results. In comparison with the calculated DCS for the S atom, atomic-like behavior for the angular distributions in both the OCS and CS2 scattering systems is observed. Integrated elastic cross sections are obtained by extrapolating the experimental measurements, with the aid of the theoretical calculations, for those scattering angles below 10° and above 150°. These values are then compared with the available total cross sections. [ABSTRACT FROM AUTHOR]

This study is to improve understanding of nonlinear optics through investigating the microstructures of carbon disulfide (CS2) liquid, an important nonlinear optical material. First principles methods are employed in this work to investigate the structure, vibrational spectra, and the 2nd hyperpolarizabilites of CS2 clusters up to tetramers. Three types of molecular arrangements of clusters with different sizes are identified. The cluster conformations are prone to inter-converting under external disturbance due to the weak interactions among molecules. The correlation between the nonlinear optical properties and the conformation of CS2 clusters are studied in detail in this work. [ABSTRACT FROM AUTHOR]

In this paper, the nanostructural organization and subpicosecond intermolecular dynamics in the mixtures of CS2 and the room temperature ionic liquid (IL) 1-pentyl-3-methylimidazolium bis{(trifluoromethane)sulfonyl}amide ([C5mim][NTf2]) were studied as a function of concentration using molecular dynamics (MD) simulations and optical heterodyne-detected Raman-induced Kerr effect spectroscopy. At low CS2 concentrations (<10 mol.% CS2/IL), the MD simulations indicate that the CS2 molecules are localized in the nonpolar domains. In contrast, at higher concentrations (≥10 mol.% CS2/IL), the MD simulations show aggregation of the CS2 molecules. The optical Kerr effect (OKE) spectra of the mixtures are interpreted in terms of an additivity model with the components arising from the subpicosecond dynamics of CS2 and the IL. Comparison of the CS2-component with the OKE spectra of CS2 in alkane solvents is consistent with CS2 mainly being localized in the nonpolar domains, even at high CS2 concentrations, and the local CS2 concentration being higher than the bulk CS2 concentration. [ABSTRACT FROM AUTHOR]

Sets of experimental data on the Cs2 a3Σu+ and 1g (33Π1g) states, including the bound-bound and bound-free fluorescence spectra, are analyzed simultaneously to produce the potential energy curves of both states in the form of the Morse long range multiparameter function. The attractive branch of the a3Σu+ state potential is improved relative to the one reported in our earlier work [F. Xie, V. B. Sovkov, A. M. Lyyra, D. Li, S. Ingram, J. Bai, V. S. Ivanov, S. Magnier, and L. Li, J. Chem. Phys. 130, 051102 (2009)], in which the data on this state alone were analyzed. Besides, the new potential of this state also includes the repulsive branch in the range spanned by the bound-free fluorescence spectra. We have not found experimental evidence of the double minimum character of the 33Π1g state potential, predicted by ab initio calculations, at least up to v = 8. This fact testifies that the upper state observed is better described by the Hund coupling case (c), in which the case (a) electronic basis states are intermixed by the strong spin-orbit interaction. [ABSTRACT FROM AUTHOR]

Infrared spectra of the CS2 dimer are observed in the region of the CS2 ν3 fundamental band (∼1535 cm-1) using a tunable diode laser spectrometer. The weakly bound complex is formed in a pulsed supersonic slit-jet expansion of a dilute gas mixture of carbon disulfide in helium. Contrary to the planar slipped-parallel geometry previously observed for (CO2)2, (N2O)2, and (OCS)2, the CS2 dimer exhibits a cross-shaped structure with D2d symmetry. Two bands were observed and analyzed: the fundamental (C-S asymmetric stretch) and a combination involving this mode plus an intermolecular vibration. In both cases, the rotational structure corresponds to a perpendicular (ΔK = ±1) band of a symmetric rotor molecule. The intermolecular center of mass separation (C-C distance) is determined to be 3.539(7) Å. Thanks to symmetry, this is the only parameter required to characterize the structure, if the monomer geometry is assumed to remain unchanged in the dimer. From the band centers of the fundamental and combination band an intermolecular frequency of 10.96 cm-1 is obtained, which we assign as the torsional bending mode. This constitutes the first high resolution spectroscopic investigation of CS2 dimer. [ABSTRACT FROM AUTHOR]

The binding energy spectrum of carbon disulphide (CS2) in the energy range of 9-23 eV has been measured by a high-resolution (e,2e) spectrometer employing asymmetric noncoplanar kinematics at an impact energy of 2500 eV plus the binding energy. Taking the advantage of the high energy resolution of 0.54 eV, four main peaks and five satellites in the outer-valence region are resolved. The assignments and pole strengths for these satellite states are achieved by comparing the experimental electron momentum profiles with the corresponding theoretical ones calculated using Hartree-Fock and density functional theory methods. The results are also compared in detail with the recent SAC-CI general-R calculations. General agreement is satisfactory, while the present experiment suggests cooperative contributions from 2Πu, 2Σg+ states to satellite 2 and 2Σg+, 2Πg states to satellite 3. Besides, relatively low pole strength for X 2Πg state is obtained which contradicts all the theoretical calculations [2ph-TDA, ADC(3), SAC-CI general-R, ADC(4)] so far. [ABSTRACT FROM AUTHOR]

Irradiation of a p-H2 matrix containing Cl2 and CS2 at 3.3 K with laser emission at 340 nm followed by annealing of the matrix produced main features at 1479.5 and 1480.8 cm-1. These lines are attributed to ν1 (SCS antisymmetric stretching) mode of ClSCS. Irradiation of the matrix at 355 nm decomposes ClSCS. Products CS (1272.2 and 1271.1 cm-1), ClCS (1193.9/1191.9 and 637.5 cm-1), and ClSC (1137.0 cm-1) were observed upon annealing. The assignments were based on comparison of observed vibrational wavenumbers and 13C- and 34S-isotopic ratios with those predicted with density-functional theories (B3LYP and BPW91/aug-cc-pVTZ). These results demonstrate that the cage effect of solid p-H2 is diminished so that isolated Cl was produced via photodissociation of Cl2 in situ and subsequently reacted with CS2 to form ClSCS, but not ClC(==S)SCl, upon annealing; typically ClC(==S)SCl was produced as the major product on irradiation of noble-gas matrices containing Cl2 and CS2. Observation of ClSCS but not ClCS2 is consistent with the theoretical prediction that only formation of the former proceeds via a barrierless path. Similarly, upon irradiation of ClSCS at 355 nm, Cl, CS, and CS2 were produced; subsequent annealing of the irradiated matrix produced ClSC and ClCS via barrierless paths. [ABSTRACT FROM AUTHOR]

The parameters of fullerene C60 dissolved in carbon disulfide CS2 are analyzed by small-angle neutron scattering (SANS) in a wide interval of momentum transfer. To exclude the influence of nonequilibrium conditions, the solutions are prepared without applying shaking, stirring or ultrasound. No indication of the equilibrium cluster state of C60 (with the cluster size below 60 nm) in the final solutions is revealed. Molecular dynamic simulations are complementary used to find out the partial volume of C60 in CS2 and the scattering contribution of the solvent organization at the interface with the fullerene molecule, which is shown to be small. Among several approaches for describing SANS data the preference is given to the model, which takes into account the presence of stable C60 dimers (comprising 10% of the total particle number density) in the solution. [ABSTRACT FROM AUTHOR]

Irradiation of a p-H2 matrix containing Cl2 and CS2 at 3.3 K with laser emission at 340 nm followed by annealing of the matrix produced main features at 1479.5 and 1480.8 cm-1. These lines are attributed to ν1 (SCS antisymmetric stretching) mode of ClSCS. Irradiation of the matrix at 355 nm decomposes ClSCS. Products CS (1272.2 and 1271.1 cm-1), ClCS (1193.9/1191.9 and 637.5 cm-1), and ClSC (1137.0 cm-1) were observed upon annealing. The assignments were based on comparison of observed vibrational wavenumbers and 13C- and 34S-isotopic ratios with those predicted with density-functional theories (B3LYP and BPW91/aug-cc-pVTZ). These results demonstrate that the cage effect of solid p-H2 is diminished so that isolated Cl was produced via photodissociation of Cl2 in situ and subsequently reacted with CS2 to form ClSCS, but not ClC(==S)SCl, upon annealing; typically ClC(==S)SCl was produced as the major product on irradiation of noble-gas matrices containing Cl2 and CS2. Observation of ClSCS but not ClCS2 is consistent with the theoretical prediction that only formation of the former proceeds via a barrierless path. Similarly, upon irradiation of ClSCS at 355 nm, Cl, CS, and CS2 were produced; subsequent annealing of the irradiated matrix produced ClSC and ClCS via barrierless paths. [ABSTRACT FROM AUTHOR]

With an interest in finding the fragility for a simple, single component, molecular glassformer, we have determined the dielectric relaxation and glass transition behavior for a series of glasses in the CS2–S2Cl2 and CS2-toluene systems. Crystallization of CS2 can be completely avoided down to the composition 20 mol% second component, and the fragility proves almost independent of CS2 content in each system. Since the glass temperature Tg obtained from both thermal studies and from dielectric relaxation (using Tg,diel=Tτ=100 s) is quite linear over the whole composition range in each system, and since relaxation time data for pure CS2 fall on the same master plot when scaled by the linearly extrapolated Tg value, we deduce that pure CS2 has the same high fragility as the binary solutions. The value is m=86, as for ortho-terphenyl (OTP). Based on observations of independent studies for the vibrational density of states (VDoS) (of inherent structures for OTP and instantaneous, at-temperature structures for CS2), we attribute the high fragility to an excess vibrational heat capacity (defined by Cp (vib, excess)=dS(vib, excess)/d ln T) originating in the behavior of the low frequency modes of the VDoS (the boson peak modes). Both low frequency DoS and anharmonicity increase with increasing temperature, augmenting the configurational entropy drive to the top of the system energy landscape. The surprising implication is that fragility is determined in the vibrational, not configurational, manifold of microstates. [ABSTRACT FROM AUTHOR]

Spectra of triply charged carbon disulphide have been obtained by measuring, in coincidence, all three electrons ejected in its formation by photoionization. Measurements of the CS23+ ion in coincidence with the three electrons identify the energy range where stable trications are formed. A sharp peak in this energy range is identified as the 2Π ground state at 53.1±0.1 eV, which is the lowest electronic state according to ab initio molecular orbital calculations. Triple ionization by the double Auger effect is provisionally divided, on the basis of the pattern of energy sharing between the two Auger electrons into contributions from direct and cascade Auger processes. The spectra from the direct double Auger effect via S 2p, S 2s, and C 1s hole states contain several resolved features and show selectivity based on the initial charge localization and on the identity of the initial state. Triple ionization spectra from single Auger decay of S 2p-based core-valence states CS22+ show retention of the valence holes in this Auger process. Related ion-electron coincidence measurements give the triple ionization yields and the breakdown patterns in triple photoionization at selected photon energies from 90 eV to above the inner shell edges. [ABSTRACT FROM AUTHOR]

The rotational spectrum of protonated carbon disulfide, HSCS+, has been detected in the centimeter-wave band in a molecular beam by Fourier transform microwave spectroscopy. Rotational and centrifugal distortion constants have been determined from ten transitions in the Ka=0 ladder of the normal isotopic species, HS13CS+, and DSCS+. The present assignment agrees well with high-level coupled cluster calculations of the HSCS+ structure, which, like earlier work, predict this isomer to be the ground state on the HCS2+ potential energy surface; HCSS+, an isomer with C2v symmetry, is predicted to lie more than 20 kcal/mol higher in energy. Other properties of HSCS+ including its dipole moment, anharmonic vibrational frequencies, and infrared intensities have also been computed at the coupled cluster level of theory with large basis sets. Because carbon disulfide possesses a fairly large proton affinity, and because this nonpolar molecule may plausibly exist in astronomical sources, HSCS+ is a good candidate for detection with radio telescopes in the submillimeter band where the stronger b-type transitions of this protonated cation are predicted to lie. [ABSTRACT FROM AUTHOR]

The rotational spectrum of protonated carbon disulfide, HSCS+, has been detected in the centimeter-wave band in a molecular beam by Fourier transform microwave spectroscopy. Rotational and centrifugal distortion constants have been determined from ten transitions in the Ka=0 ladder of the normal isotopic species, HS13CS+, and DSCS+. The present assignment agrees well with high-level coupled cluster calculations of the HSCS+ structure, which, like earlier work, predict this isomer to be the ground state on the HCS2+ potential energy surface; HCSS+, an isomer with C2v symmetry, is predicted to lie more than 20 kcal/mol higher in energy. Other properties of HSCS+ including its dipole moment, anharmonic vibrational frequencies, and infrared intensities have also been computed at the coupled cluster level of theory with large basis sets. Because carbon disulfide possesses a fairly large proton affinity, and because this nonpolar molecule may plausibly exist in astronomical sources, HSCS+ is a good candidate for detection with radio telescopes in the submillimeter band where the stronger b-type transitions of this protonated cation are predicted to lie. [ABSTRACT FROM AUTHOR]

We report absolute measurements of the nonlinear refractive index on carbon disulfide (CS2) and fused silica. These materials are commonly used as standard references in nonlinear optical experiments. To obtain more accurate values than those usually used, we have combined the z-scan method inside a 4-f imaging system (in order to analyze the spatial distortion of the diffracted pump beam) with the "Kerr shutter" experiment (to evaluate the temporal pulse width durations for three different wavelengths such as 1064, 532, and 355 nm). We obtained surprisingly n2 values one order of magnitude less than the one usually taken into account in the picosecond regime and a more significant dispersion of the nonlinear refraction index. Experimental and simulated Z-scan transmittance profiles as well as acquired autocorrelation functions in the Kerr-gating experiments are presented here in order to validate our measurements. [ABSTRACT FROM AUTHOR]

We present neutron and x-ray scattering data (a 2N+X experiment) of liquid CO2 and CS2 at a density of about 10 molecules/nm3. Because the scattering length contrast of the carbon isotope is very small and, in fact, smaller than anticipated from standard scattering length tables, a direct partial structure factor determination via matrix inversion gives unconvincing results. Instead we search for the best representation of the three independent scattering data sets by a simulation of rigid molecules interacting via a 12-6-1 potential, furthermore restricting the pressure p, the density ρ, and the temperature T to the experimental values. We show that a 12-6-1 potential is completely adequate to describe the structure of CO2; for CS2 we find that the best 12-6-1 potential still slightly overestimates the height of the sulfur-sulfur pair-distribution function gSS. Orientational correlations reflect the similarities much more than the differences of the two molecular systems. The distinct differences in the atom-atom pair distribution functions of CO2 and CS2 do not mean that their structures are radically different and the comparison with the crystalline structures is somewhat deceptive. A linear transformation, wherein all the parameters describing the interaction and the geometry of CS2 are changed to those of CO2, allows us to point out the physical parameters which may be responsible for the differences or similarities in thermodynamic behavior (pressure) and structures (orientations) between the two liquids. [ABSTRACT FROM AUTHOR]

The photodissociation of the (CS2)2- dimer anion, known to exist in the form of several electronic and structural isomers, has been investigated at 532, 355, and 266 nm. The observed anionic fragments are CS2- and C2S2- at 532 nm, and C2S2-, CS2-, CS3-, S2-, and S- at 355 and 266 nm. In addition to the photon energy, the fractional yields of the photofragments depend on the ion source conditions and solvation of the dimer anion. Specifically, the (C2S2-+S2-)/CS2- product ratio is significantly higher when (CS2)2- is formed in the presence of water in the precursor gas mixture, even though the parent anion itself does not include H2O. On the other hand, an abrupt decrease in the above product ratio is observed upon the addition of solvent molecules (CS2 or H2O) to the (CS2)2- anion. Since the variation of this product ratio exhibits positive correlation with the relative intensity of the photoelectron band assigned to the C2v (2B1) covalent structure of C2S4- by Habteyes et al. [J. Phys. Chem. A 112, 10134 (2008)], this structure is suggested as the primary origin of the C2S2- and S2- photoproducts. The switching of the fragmentation yield from C2S2- and S2- to other products upon solvation is ascribed to the diminished presence of the C2v (2B1) dimer-anion structure relative to the CS2- based clusters. This population shift is attributed to the more effective solvation of the latter. The CS2- based clusters are suggested as the origin of the S- photoproduct, while CS3- is formed through the secondary S-+CS2 intracluster association reaction. [ABSTRACT FROM AUTHOR]

We present a new approach for the approximation of solvent densities around solutes of arbitrary shape. Our model represents a three-dimensional (3d) Born–Green–Yvon (BGY) equation for an arbitrary solute immersed into a molecular (M) solvent, the BGY3dM model. It comprises the famous Kirkwood approximation as closure relation. The molecules of the solvent are modeled as rigid bodies by taking the limit of an infinite restoring force for the intramolecular interactions. Furthermore, short-range potentials as well as the long-range Coulomb interaction are taken into account. The resulting integro-differential equations are efficiently solved by a Picard iteration and a solution of the linearized equations using Fourier transformations. We compare the results obtained from the presented BGY3dM method with results obtained by extensive molecular dynamics simulations for a HCl-like model solvent. Furthermore, we apply the method to carbon disulfide as solvent. The overall performance of the method is promising. [ABSTRACT FROM AUTHOR]

The authors report time resolved photoelectron spectra of the 1B2(1Σu+) state of CS2 at pump wavelengths in the region of 200 nm. In contrast to previous studies, the authors find that the predissociation dynamics is not well described by a single exponential decay. Biexponential modeling of the authors’ data reveals a rapid decay pathway (τ<50 fs), in addition to a longer lived channel (τ∼350–650 fs) that displays a marked change in apparent lifetime when the polarization of the pump laser is rotated with respect to that of the probe. Since the initially populated 1B2(1Σu+) state may decay to form either S(1D) or S(3P) products (the latter produced via a spin-orbit induced crossing from a singlet to a triplet electronic surface), this lifetime observation may be rationalized in terms of changes in the relative ionization cross section of these singlet and triplet states of CS2 as a function of laser polarization geometry. The experimentally observed lifetime of the longer lived channel is therefore a superposition of these two pathways, both of which decay on very similar time scales. [ABSTRACT FROM AUTHOR]

The authors report time resolved photoelectron spectra of the 1B2(1Σu+) state of CS2 at pump wavelengths in the region of 200 nm. In contrast to previous studies, the authors find that the predissociation dynamics is not well described by a single exponential decay. Biexponential modeling of the authors’ data reveals a rapid decay pathway (τ<50 fs), in addition to a longer lived channel (τ∼350–650 fs) that displays a marked change in apparent lifetime when the polarization of the pump laser is rotated with respect to that of the probe. Since the initially populated 1B2(1Σu+) state may decay to form either S(1D) or S(3P) products (the latter produced via a spin-orbit induced crossing from a singlet to a triplet electronic surface), this lifetime observation may be rationalized in terms of changes in the relative ionization cross section of these singlet and triplet states of CS2 as a function of laser polarization geometry. The experimentally observed lifetime of the longer lived channel is therefore a superposition of these two pathways, both of which decay on very similar time scales. [ABSTRACT FROM AUTHOR]

The dissociation dynamics of the 6s and 4d Rydberg states of carbon disulfide (CS2*) are studied by time-resolved photoelectron spectroscopy. The CS2 is excited by two photons of 267 nm (pump) to the 6s and 4d Rydberg states and probed by ionization with either 800 or 400 nm. The experiments can distinguish and successfully track the time dynamics of both spin [1/2] (upper) and [3/2] (lower) cores of the excited Rydberg states, which are split by 60 meV, by measuring the outgoing electron kinetic energies. Multiple mode vibrational wave packets are created within the Rydberg states and observed through recurrence interferences in the final ion state. Fourier transformation of the temporal response directly reveals the coherent population of several electronic states and vibrational modes. The composition of the wave packet is varied experimentally by tuning the excitation frequency to particular resonances between 264 and 270 nm. The work presented here shows that the decay time of the spin components exhibits sensitivity to the electronic and vibrational states accessed in the pump step. Population of the bending mode results in an excited state lifetime of as little as 530 fs, as compared to a several picosecond lifetime observed for the electronic origin bands. Experiments that probe the neutral state dynamics with 400 nm reveal a possible vibrationally mediated evolution of the wave packet to a different Franck-Condon window as a consequence of Renner-Teller splitting. Upon bending, symmetry lowering from D∞h to C2v enables ionization to the CS2+ (B 2Πu) final state. The dissociation dynamics observed are highly mode specific, as revealed by the frequency and temporal domain analysis of the photoelectron spectra. [ABSTRACT FROM AUTHOR]

We have implemented a holographic system to study the propagation of femtosecond laser pulses with high temporal (150 fs) and spatial resolutions (4 μm). The phase information in the holograms allows us to reconstruct both positive and negative index changes due to the Kerr nonlinearity (positive) and plasma formation (negative), and to reconstruct three-dimensional structure. Dramatic differences were observed in the interaction of focused femtosecond pulses with air, water, and carbon disulfide. The air becomes ionized in the focal region, while in water long plasma filaments appear before the light reaches a tight focus. In contrast, in carbon disulfide the optical beam breaks up into multiple filaments but no plasma is measured. We explain these different propagation regimes in terms of the different nonlinear material properties. [ABSTRACT FROM AUTHOR]

The fifth-order two-dimensional (2D) Raman signals have been calculated from the equilibrium and nonequilibrium (finite field) molecular dynamics simulations. The equilibrium method evaluates response functions with equilibrium trajectories, while the nonequilibrium method calculates a molecular polarizability from nonequilibrium trajectories for different pulse configurations and sequences. In this paper, we introduce an efficient algorithm which hybridizes the existing two methods to avoid the time-consuming calculations of the stability matrices which are inherent in the equilibrium method. Using nonequilibrium trajectories for a single laser excitation, we are able to dramatically simplify the sampling process. With this approach, the 2D Raman signals for liquid xenon, carbon disulfide, water, acetonitrile, and formamide are calculated and discussed. Intensities of 2D Raman signals are also estimated and the peak strength of formamide is found to be only five times smaller than that of carbon disulfide. [ABSTRACT FROM AUTHOR]

Femtosecond degenerate four-wave mixing (fs-DFWM) rotational coherence spectroscopy (RCS) has been used to determine the rotational and centrifugal distortion constants of the 00 00 ground and 01 10 vibrationally excited states of gas-phase CS2. RCS transients were recorded over the 0–3300 ps optical delay range, allowing the observation of 87 recurrences. The fits yield rotational constants B00 00=3.271 549 2(18) GHz for 12C32S2 and B00 00=3.175 06(21) GHz for the 12C32S34S isotopomer. The rotational constants of the degenerate 01 10 bending level of 12C32S2 are B01 10=3.276 72(40) and 3.279 03(40) GHz for the e and f substrates, respectively. These fs-DFWM rotational constants are ten times more accurate than those obtained by CO2 laser/microwave heterodyne measurements and are comparable to those obtained by high-resolution Fourier transform infrared spectroscopy. Ab initio calculations were performed at two levels, second-order Mo\ller-Plesset theory and coupled-cluster singles, doubles, and iterative triples [CCSD(T)]. The equilibrium and vibrationally averaged C==S distances were calculated using large Dunning basis sets. An extrapolation procedure combining the ab initio rotational constants with the experiment yields an equilibrium C==S bond length of 155.448 pm to an accuracy of ±20 fm. The theoretical C==S bond length obtained by a complete basis set extrapolation at the CCSD(T) level is re(C==S)=155.579 pm, or 0.13 pm longer than that in the experiment. [ABSTRACT FROM AUTHOR]

The à 2Πu-X 2Πg electronic band system of the jet-cooled CS2+ ion has been studied by laser-induced fluorescence and wavelength-resolved emission techniques. The ions were produced in a pulsed electric discharge jet using a precursor mixture of carbon disulfide vapor in high-pressure argon. Rotational analysis of the high-resolution spectrum of the 2Π3/2 component of the 000 band gave linear-molecule molecular structures of r0″=1.5554(10) Å and r0′=1.6172(12) Å. Renner-Teller analyses of the vibronic structure in the spectra showed that the ground-state spin-orbit splitting (A=-447.0 cm-1) is much larger than that of the excited state (A=-177.5 cm-1), but that the Renner-Teller parameters are of similar magnitude and that a strong ν1-2ν2 Fermi resonance occurs in both states. Previous analyses of the vibronic structure in the ground and excited states of the ion from pulsed field-ionization–photoelectron data are shown to be substantially correct. [ABSTRACT FROM AUTHOR]

In a discharged supersonic jet of acetonitrile and carbon disulfide, we have for the first time observed an electronic transition of the NC[sub 3]S radical using laser-induced fluorescence (LIF) spectroscopy. A progression originating from the C–S stretching mode of the upper electronic state appears in the excitation spectrum. Each band of the progression has a polyad structure due to anharmonic resonances with even overtones of bending modes. Rotationally resolved spectra have been observed by high-resolution laser scans, and the electronic transition is assigned to à [sup 2]Π[sub i]–X [sup 2]Π[sub i]. For the vibronic origin band, the position and the effective rotational constant of the upper level have been determined to be 21 553.874(1) and 0.046 689(4) cm-1, respectively. The dispersed fluorescence spectrum from the zero vibrational level of à [sup 2]Π[sub 3/2] has also been observed; its vibrational structure is similar to that of the LIF excitation spectrum, showing a prominent C–S stretching progression with polyad structures. The vibrational frequencies of the C–S stretching mode in the ground and excited electronic states are determined to be 550 and 520 cm-1, respectively. Fluorescence decay profiles have been measured for several vibronic levels of the à state. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A new theory for the fifth order Raman response function, R[sup (5)](t[sub 1],t[sub 2]), is presented. Using this result, R[sup (5)](t[sub 1],t[sub 2]) is shown to have a classical limit given by a combination of time derivatives of the real and imaginary parts of a two time correlation function (TCF) of the polarizability. In contrast with one time correlation functions, no exact analytic relationship exists between the real and imaginary parts of the quantum mechanical TCF that would allow the classical limit to be written in terms of classical TCF’s. Writing the nonlinear response function in terms of classical TCF’s would allow R[sup (5)](t[sub 1],t[sub 2]) to be calculated with minimal computational effort, in contrast to existing (exact) classical formulations. However, a simple approximate relationship is shown to exist between the real and imaginary parts of the two time TCF for a harmonic system with nonlinear polarizability. In the spirit of quantum correction, this relationship is used to write the exact classical response function in terms of classical TCF’s. The resulting TCF expression is then calculated from (fully anharmonic) molecular dynamics calculations supplemented by a suitable spectroscopic (polarizability) model. The approximate expression is demonstrated to have correct limiting behaviors and leads to a two-dimensional spectrum for ambient carbon disulfide in excellent agreement with existing experimental and theoretical work. The proposed approach makes the calculation of fifth order response functions practical for a wide variety of chemically interesting systems. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Dissociative and nondissociative scattering of low energy CS[SUP+,SUB2] ions from a self-assembled (CS)2 monolayer surface of fluorinated alkylthiol [CF[SUB3](CF[SUB2])[SUB9]CH[SUB2]CH[SUB2]SH] on vapor deposited gold has been studied using a modified crossed-beam instrument. Dissociation of CS[SUP+,SUB2] ions begins at ∼30 eV (been studied using a modified crossed-beam instrument. Dissociation of CS[SUP+,SUB2] ion kinetic energy, much higher than the thermochemical threshold of 4.7 eV for the lowest energy dissociation channel forming S[SUP+]. This product channel is dominant up to the ion energy of ∼50 eV, the highest energy accessible by this instrument. Both inelastically scattered parent ions and product ions leave the surface with very low kinetic energies, demonstrating that most of the ions' kinetic energy is taken up by the surface rather than transferred into internal modes of recoiling ions. The scattered ion intensity maximum is found between the specular angle and the surface parallel. At all energies studied, primary ion intensity remains higher than that of fragment ions. Also, the intensity of S[SUP+] fragment ions is higher than that of CS[SUP+] fragment ions, suggesting that the distribution of the recoiling CS[SUP+,SUB2] ions extends only slightly above the thresholds for the two (internal excitation of the recoiling CS[SUP+,SUB2] product channels. A comparison of the relative intensities of the fragment ions with those from earlier collision-induced dissociation study of the CS[SUP+,SUB2] ions with xenon suggests that only ∼6.5 and ∼7.5 eV are transferred into internal modes for 30.6 and 49.8 eV energy collisions, respectively. This is lower than the energy transferred into internal modes in the gas phase collision-induced dissociation process, for which the center-of-mass collision energy is well defined. We infer from our observations that the effective mass of the surface collision partner is much less than that of the... [ABSTRACT FROM AUTHOR]

Vacuum ultraviolet pulsed field ionization-photoelectron (PFI-PE) spectra for CS[SUB2] have been obtained in the energy range of 13.2-17.6 eV, revealing complex vibronic structures for the CS[SUB2,SUP+](&Btilde;[SUP2]∑[SUBu,SUP+] and &Ctilde;[SUP2]∑[SUBg,SUP+]) states. The PFI-PE spectra for CS[SUB2,SUP+](&Btilde;[SUP2]∑[SUBu,SUP+] and &Ctilde;[SUP2]∑[SUBg,SUP+]) are dominated by v[SUB1,SUP+] (symmetric stretching) mode. However, PFI-PE bands due to the v[SUB2,SUP+] (bending) and v[SUB3,SUP+] (antisymmetric stretching) modes with both even and odd quanta are clearly resolved. The simulation of rotational contours resolved in the origin PFI-PE bands yields accurate ionization energies of 14.4742±0.0005 eV (116742±4 cm[SUP-1]) and 16.1883±0.0005 eV (130567±4 cm[SUP-1]) for the formation of CS[SUB2,SUP+](&Btilde;[SUP2]∑[SUBu,SUP+] and &Ctilde;[SUP2]∑[SUBg,SUP+]) states from CS[SUB2](&Xtilde;[SUP1]∑[SUBg,SUP+]), respectively. The PFI-PE bands for [SUP2]∑[SUBu,SUP+](3[SUB0,SUP3]) and [SUP2]∑[SUBg,SUP+](3[SUB0,SUP3]) at 14.805 and 14.965 eV, which are in near energy resonance with the 0 K dissociation thresholds for the formation of S[SUP+]([SUP4]S)+CS(&Xtilde;[SUP1]∑[SUP+]; v"=0 and 1) from CS[SUB2], respectively, are found to be enhanced. These enhancements are rationalized by the prompt dissociation of excited CS[SUB2] in high-n (n&ges;100) Rydberg states prior to PFI. Three-dimensional potential energy functions (PEFs) for CS[SUB2,SUP+](2[SUP2]II[SUBu], &Btilde;[SUP2]∑[SUBu,SUP+], and &Ctilde;[SUP2]∑[SUBg,SUP+]) states have been generated theoretically using the complete active space self-consistent field and internally contracted multireference configuration interaction methods. On the basis of these PEFs, the harmonic frequencies for CS[SUB2,SUP+](2[SUP2]II[SUBu], (&Btilde;[SUP2]∑[SUBu,SUP+] and &Ctilde;[SUP2]∑[SUBg,SUP+]) and vibronic energy levels for CS[SUB2,SUP+](&Btilde... [ABSTRACT FROM AUTHOR]

The subpicosecond dynamics of binary mixtures of carbon disulfide and alkane have been studied using third-order time-resolved Raman techniques. Both the anisotropic and the isotropic responses were investigated. These depend differently on many-body contributions to the first-order susceptibility and probe different modes in the liquid. The anisotropic response is dominated by single molecule effects, whereas the isotropic response is completely determined by many-body contributions since the single molecule response vanishes. To interpret the experimental results, molecular dynamics simulations were performed on model mixtures. The effect of dilution on the subpicosecond response cannot be explained by many-body effects in the first-order susceptibility alone. Aggregation due to permanent quadrupole moments on the carbon disulfide molecules and density changes upon dilution are also inadequate explanations for the observed effect. Apparently the character of the many-body dynamics itself is modified by the change of the molecular force fields, when carbon disulfide molecules are replaced by alkanes. [ABSTRACT FROM AUTHOR]

A model of the polarizability of carbon disulfide dimers was constructed, using polarizabilities from accurate time-dependent density functional theory calculations as reference. This direct reaction field model takes dipole-induced dipole effects, induced multipole effects and effects due to the overlap of the electronic clouds into account in an approximate way. The importance of the induced multipole and the overlap effects is investigated. This polarizability model is subsequently used to calculate the third-order time-domain Raman response of liquid carbon disulfide. These results are compared to experimental data and earlier calculated response in which only dipole-induced dipole effects on the polarizability were included. The multipole effects are found to give a significant contribution to the subpico second part of the third-order Raman response. [ABSTRACT FROM AUTHOR]

Studies the ultrafast predissociation dynamics of CS[sub 2] molecules excited to the [sup 1] B[sub 2]([sup 1] Epsilon [sub mu][sup +] electronic state by femtosecond laser pulses with 6.0-6.4- eV photon energy. Reflection of the barrier of the transition from the bent to a quasilinear geometry of the excited CS[sub 2] molecule.

Studies the behavior of self-diffusion in supercooled liquid carbon disulphide (CS[sub2]). Determination of self-diffusion coefficient by computer simulation for seven densities and eight temperatures; Detection of activation energies and Arrhenius behaviors at different densities and temperatures.

Observes the rotational spectra of seven isotopomers of the sulphur dioxide and carbon disulphide van der Waals dimer with a Fourier transform microwave spectrometer. Determination of the rotational constants for the normal species; Center of mass of the two monomers; Alignment of rotational axis.

Focuses on the measurement of the excitation Zeeman spectra and the change with an external magnetic field of the 9 U band of carbon disulfide by using the technique of laser spectroscopy. Attribution of Zeeman splittings in the excited levels; Estimation of the rotational temperature of the CS[sub 2] beam.