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We have demonstrated the two-color vacuum ultraviolet (VUV)-infrared (IR) photoinduced Rydberg ionization (PIRI) experiment. Trichloroethene (ClCH==CCl[sub 2]) and trans-2-butene (trans-CH[sub 3]CH==CHCH[sub 3]) were prepared in Rydberg states in the range of effective principal quantum number n[sup *]≈7–93 by VUV excitation prior to IR-induced autoionization. The observed VUV-IR-PIRI spectra are found to be independent of n[sup *], suggesting that the electron Rydberg orbital is conserved, i.e., the Rydberg electron is behaving as a spectator during the excitation process. The observed IR active C–H stretching vibrational frequencies ν[sub 12][sup +]=3072±5 cm[sup -1] for ClCH==CCl[sub 2][sup +] and ν[sub 23][sup +]=2908±3 cm[sup -1], ν[sub 25][sup +]=2990±10 cm[sup -1] and ν[sub 30][sup +]=3022±10 cm[sup -1] for trans-CH[sub 3]CH==CHCH[sub 3][sup +] are compared with predictions based on ab initio quantum-chemical procedures and density functional calculations. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

By employing the two-color infrared (IR)-vacuum ultraviolet (VUV) laser photoionization (PI) schemes, we have determined the C[Single_Bond]H stretching frequencies ν[sub 12]=3097.7 cm[sup -1] for trichloroethene (CHCl==CCl[sub 2]) and ν[sub 12][sup +]=3066 cm[sup -1] for CHCl==CCl[sub 2][sup +]. On the basis of the IR-VUV-pulsed field ionization-photoelectron (PFI-PE) measurement, the ratio of the state-to-state PI cross section for CHCl==CCl[sub 2][sup +](ν[sub 12][sup +]=1)←CHCl==CCl[sub 2](ν[sub 12]=1) to that for the formation of the ground state ion from the ground state neutral is determined to be 0.24. The VUV-PI efficiency (PIE) spectrum for CHCl==CCl[sub 2] and IR-VUV-PIE spectrum for CHCl==CCl[sub 2](ν[sub 12]=1) show that the state-to-state PI cross section for the formation of CHCl==CCl[sub 2][sup +] in the ground state from CHCl==CCl[sub 2](ν[sub 12]=1) is ≈0.006 that from CHCl==CCl[sub 2] in its ground state. As expected, the IR-VUV-PIE onset for CHCl==CCl[sub 2](ν[sub 12]=1) exhibits less hot-band tailing than the VUV-PIE onset for supersonically cooled CHCl==CCl[sub 2]. After taking into account the ν[sub 12] frequency, the ionization energy values for CHCl==CCl[sub 2] determined based on the IR-VUV-PIE and VUV-PFI-PE measurements are found to be in excellent agreement. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The single-photon pulsed field ionization photoelectron (PFI-PE) spectrum of trans-2-butene (trans-CH[sub 3]CH=CHCH[sub 3]) in the energy range of 73 500–75 850 cm-1 has been measured using vacuum ultraviolet laser sources. The semi-empirical simulation of fine structures resolved in the original PFI-PE band yields a value of 73 624.7±2.0 cm[sup -1] for the ionization energy (IE) of trans-2-butene. The vibrational bands for trans-CH[sub 3]CH=CHCH[sub 3][sup +] resolved in the PFI-PE spectrum are assigned based on ab initio calculations of the vibrational frequencies and Franck-Condon factors (FCFs) for ionization transitions. This assignment has provided reliable vibrational frequencies (ν[sub 1][sup +]=104 cm[sup -1], ν[sub 2][sup +]=127 cm[sup -1], ν[sub 3][sup +]=131 cm[sup -1], ν[sub 5][sup +]=484 cm[sup -1], ν[sub 8][sup +]=798 cm[sup -1], ν[sub 13][sup +]=1164 cm[sup -1], ν[sub 14][sup +]=1264 cm[sup -1], ν[sub 16][sup +]=1307 cm[sup -1], ν[sub 20][sup +]=1407 cm[sup -1], and ν[sub 22][sup +]=1567 cm[sup -1]) for trans-CH[sub 3]CH=CHCH[sub 3][sup +]. The PFI-PE spectrum is compared to the recently reported PFI-photoion (PFI-PI) spectrum for trans-2-butene. The major difference observed between the PFI-PE and PFI-PI spectra is that the intensities for excited vibrational bands were significantly suppressed or indiscernible in the PFI-PI spectrum, suggesting that the lifetimes for high-n Rydberg states associated with these excited vibrational bands were greatly reduced under the conditions used in the PFI-PI study. The experimental conditions used in the PFI-PI study also led to an IE value of about 20 cm-1 lower than that obtained in the PFI-PE measurement. We have also reassigned the vibrational bands resolved in the PFI-PE spectrum for cis-2-butene based on the FCF calculation and a more reliable set of theoretical vibrational frequencies. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Discusses an experimental and theoretical study of the spin-orbit interaction for carbon dioxide and oxygen. Rotationally resolved pulsed field ionization photoelectron (PFI-PE); Angular momentum coupling factor for the photoionization of the present carbon dioxide system.

Studies rotationally resolved pulsed filed ionization photoelectron (PFI-PE) spectra of NO at a specific energy range covering ionization transitions. PFI-PE bands for NO that represent the first rotationally resolved spectroscopic data for these states; Increase in inelastic cross sections for collisions.

Reports that rotationally resolved pulsed field ionization photoelectron (PFI-PE) spectra have been obtained for oxygen in the energy range of 12.05-18.15 eV. Relative vibrational band intensities for O[sup +][sub 2]; Spectral simulation and assignment of rotational branches.

Reports on the acquisition of rotationally resolved pulsed field ionization photoelectron spectra of oxygen covering the ionization transitions of O[sup +][sub 2](B [sup 2]Sigma[sup -][sub g], v[sup +]=0-7,N[sup +]...O[sub 2](X [sup 3]Sigma[sup -][sub g], v''=0,N''). Pulsed field ionization photoelectron measurements; Measurements of lifetimes for high-n Rydberg states.

Describes the high-resolution energy-selected kinetic energy release measurement for the photoionization process SF(sub 6)+hv...SF( sub 5+)+F+e. Thermochemical threshold for the process; Calculated heats of formation at 0 K for SF(sub 5+) and SF(sub 5); Design and detailed performance of the chemical dynamics beamline.

Studies acetophenone at 193 and 248 nanometer. Laser photofragmentation time-of-flight mass; Secondary products yield; Heats of formation; Ultraviolet photochemistry of alkyl ketones and related molecules.

Improves a newly developed experimental scheme for high resolution pulsed field ionization photoelectron (PFI-PE) studies of oxygen using the high resolution monochromatized multibunch undulator synchroton of the chemical dynamics beamline at the advanced light source. Advantage of the scheme for PFI-PE measurements to have no contamination by background electrons.

Integral collision-induced dissociation (CID) cross sections at center-of-mass (CM) energies ranging from threshold to 22 eV and product ion recoil velocity distributions are presented for O[sub 2][sup +]+Ne(Ar) collisions. The O[sub 2][sup +] ions are produced in an electron impact ion source and thus have ∼0.5 eV of vibrational energy. The O[sub 2][sup +]+Ne CID cross sections are observed at energies below the 0 K thermodynamic threshold of 6.66 eV, implying the possibility of significant vibrational effects. A second CID threshold is apparent at 9±1 eV. This is close to the charge-transfer (CT) threshold energy. No CT products are observed. The O[sub 2][sup +]+Ar CID cross section rises rapidly above a relative translational energy onset of 7.5±0.2 eV and reaches a maximum value of ∼0.8 Å2 at 14 eV (CM). A CT onset of 6.0±0.2 eV is observed which is close to the thermodynamic threshold for CID. The energy dependence of the CT cross section is very similar to the CID cross section except for a small step at energies where CID becomes efficient. The CID recoil velocity distributions near threshold are centered at the CM velocity and shift to forward preference at higher energies. The O[sub 2][sup +]+Ar CT recoil velocities are forward scattered near threshold and become centered with respect to the CM velocity at energies where competition with CID is apparent. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The vacuum ultraviolet (VUV) pulsed field ionization-photoelectron (PFI-PE) spectra for CO[sub 2] have been measured in the energy range of 17.2-19.0 eV, showing complex vibronic structures for the CO[sub 2][sup +](A [sup 2]Π[sub u] and B [sup 2]Σ[sub u][sup +]) states. The PFI-PE spectra for CO[sub 2][sup +](A [sup 2]Π[sub u] and B [sup 2]Σ[sub u][sup +]) are dominated by the v[sub 1][sup +] (symmetric stretching) vibrational progressions, and weak bands due to excitation of both even and odd quanta of the v[sub 2][sup +] (bending) and v[sub 3][sup +] (antisymmetric stretching) modes are observed in the VUV-PFI-PE spectra. The simulation of rotational contours resolved in the PFI-PE vibronic bands associated with excitation to CO[sub 2][sup +](A [sup 2]Π[sub 3/2,1/2u];v[sub 1][sup +]=0-5,v[sub 2][sup +]=0,v[sub 3][sup +]=0) and CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +];0,0,0) has yielded accurate ionization energies for the formation of these states from CO[sub 2](X [sup 1]Σ[sub g][sup +]). Three-dimensional potential energy functions (PEFs) for CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +]) have also been generated theoretically using the complete active space self-consistent field and internally contracted multireference configuration interaction methods. Based on these PEFs, vibrational energy levels for CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +]), together with the Franck-Condon factors for their formation from CO[sub 2](X [sup 1]Σ[sub g][sup +]), have been calculated. With the guide of these theoretical predictions, the vibrational bands resolved in the PFI-PE spectrum for CO[sub 2][sup +](B [sup 2]Σ[sub u][sup +]) have been satisfactorily assigned. This assignment reveals the nature of many vibrational PFI-PE bands as originated from anharmonic resonance interactions and members of Fermi polyads. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The vacuum ultraviolet pulsed field ionization-photoelectron (PFI-PE) spectra for CO[sub 2] have been measured in the energy range of 13.6-14.7 eV, revealing complex vibronic structures for the ground CO[sub 2][sup +](X [sup 2]Π[sub g]) state. Many vibronic bands for CO[sub 2][sup +](X [sup 2]Π[sub g]), which were not resolved in previous photoelectron studies, are identified in the present measurement based on comparison with available optical data and theoretical predictions. As observed in the HeI photoelectron spectrum of CO[sub 2], the PFI-PE spectrum is dominated by the symmetry allowed ν[sub 1][sup +] (symmetric stretch) vibrational progression for CO[sub 2][sup +](X [sup 2]Π[sub g]). However, PFI-PE vibronic bands due to excitation of the symmetry disallowed ν[sub 2][sup +] (bending) and ν[sub 3][sup +] (asymmetric stretch) modes with both odd quanta, together with the symmetry allowed even quanta excitations, are clearly discernible. The simulation of rotational contours resolved in PFI-PE vibronic bands associated with excitation to the (ν[sub 1][sup +]=0-1, ν[sub 2][sup +]=0-2, ν[sub 3][sup +]=0) vibrational levels has yielded accurate ionization energies for the formation of these vibronic states from CO[sub 2](X [sup 1]Σ[sub g][sup +]). © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have obtained rotationally resolved pulsed-field ionization photoelectron (PFI-PE) spectra for O[sub 2] in the energy range of 17.05-18.13 eV, covering the ionization transitions O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]=0-12,N[sup +])←O[sub 2](X [sup 3]Σ[sub g][sup -],v[sup ″]=0,N[sup ″]). Although these O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]) PFI-PE bands have significant overlaps with vibrational bands for O[sub 2][sup +](a [sup 4]Π[sub u]) and O[sub 2][sup +](X [sup 2]Π[sub g]), we have identified all the O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]=0-12) bands by simulation of spectra obtained using supersonically cooled O[sub 2] samples with rotational temperatures approx. 20 and 220 K. While these v[sup +]=0-12 PFI-PE bands represent the first rotationally resolved photoelectron data for O[sub 2][sup +](A [sup 2]Π[sub u]), the PFI-PE bands for O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]=9 and 10) are the first rotationally resolved spectroscopic data for these levels. The simulation also allows the determination of accurate ionization energies, vibrational constants, and rotational constants for O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]=0-12). The analysis of the PFI-PE spectra supports the conclusion of the previous emission study that the O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]=9 and 10) states are strongly perturbed by a nearby electronic state. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have obtained rotationally resolved pulsed field ionization-photoelectron (PFI-PE) spectra of O[sub 2] in the energy range of 16.0-18.0 eV, covering ionization transitions O[sub 2][sup +](a [sup 4]Π[sub u], v[sup +]=0-18,J[sup +])←O[sub 2](X [sup 3]Σ[sub g][sup .], v[sup ″]=0,N[sup ″]). Although these vibrational PFI-PE bands for O[sub 2][sup +](a [sup 4]Π[sub u], v[sup +]) have significant overlaps with those for O[sub 2][sup +](X [sup 2]Π[sub g]) and O[sub 2][sup +](A [sup 2]Π[sub u]), we have identified all O[sub 2][sup +](a [sup 4]Π[sub u], v[sup +]=0-18) bands by simulation of spectra obtained using supersonically cooled O[sub 2] samples with rotational temperatures approx. 20 and 220 K. While the v[sup +]=4-18PFI-PE bands represent the first rotationally resolved photoelectron data for O[sub 2][sup +](a [sup 4]Π[sub u]), the PFI-PE bands for O[sub 2][sup +](a [sup 4]Π[sub u], v[sup +]=10-18) are the first rotationally resolved spectroscopic data for these levels. The simulation also allows the determination of accurate ionization energies, vibrational constants, and rotational constants for O[sub 2][sup +](a [sup 2]Π[sub u], v[sup +]=0-18). The observed intensities of spin-orbit components for the majority of O[sub 2][sup +](a [sup 2]Π[sub u], v[sup +]) vibrational bands are in accordance with the forced spin-orbit/rotational autoionization mechanism. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]