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This paper presents pulsed-field ionization, zero electron kinetic energy (ZEKE) photoelectron and threshold photoionization spectra of M-X[(C[H.sub.3]).sub.3] (M = Ga, In; X = P, As). The ZEKE spectra exhibit well-resolved vibrational structures. A comparison with B3LYP calculations shows that the spectrum of In-P[(C[H.sub.3]).sub.3] arises from the [sup.1][A.sub.1] [left arrow] [sup.2]E transition and the spectra of Ga-P[(C[H.sub.3]).sub.3] and Ga-As[(C[H.sub.3]).sub.3] arise from transitions of a Jahn-Teller distorted doublet state to the [sup.1][A.sub.1] state. The intensifies of the [sup.1][A.sub.1]-[sup.2]E transition in the indium species are described with the Franck-Condon approximation, while the transitions in the gallium complexes are more complicated due to the dynamic Jahn-Teller effect. The adiabatic ionization potentials of Ga-P[(C[H.sub.3]).sub.3], In-P[(C[H.sub.3]).sub.3], and Ga-As[(C[H.sub.3]).sub.3] are 39 635, 38 930, and 40 322 [cm.sup.-1] respectively, and the ionization threshold of In-As[(C[H.sub.3]).sub.3] is -39 550 [cm.sup.-1]. The metal-ligand stretching frequencies are 143, 116, and 125 [cm.sup.-1] for [Ga.sup.+]-P, [In.sup.+]-P. and [Ga.sup.+]-As, respectively, and 96 [cm.sup.-1] for In-P. The intermolecular bending frequencies are 71, 65, and 42 [cm.sup.-1] for [Ga.sup.+]-P-C, [In.sup.+]-P-C. and [Ga.sup.+]-As-C, respectively, and 47 [cm.sup.-1] for In-P-C. In addition, ligand-based vibrational frequencies are determined for the C[H.sub.3] wag, P[C.sub.3] and As[C.sub.3] umbrella, and P-C stretching vibrations. Key words: ZEKE photoelectron, photoionization, DFT. gallium-phosphine, gallium-arsine, indium-phosphine, indium-arsine.

In NH3 is examined with single-photon zero electron kinetic energy (ZEKE) spectroscopy and density functional theory and ab initio calculations. The conclusion states that the stronger metal--ligand bonding in the ion state is due to the additional charge--dipole and covalent interactions.

The copper complexes were produced in pulsed laser vaporization molecular beams and investigated by pulsed-field ionization zero electron kinetic energy (ZEKE) spectroscopy and second-order Møller–Plesset (MP2) perturbation and hybrid B3LYP density functional theory calculations. The ground electronic states of Cu–X(CH[sub 3])[sub 3] and Cu[sup +]–X(CH[sub 3])[sub 3] (X=N,P,As) are [sup 2]A[sub 1] and [sup 1]A[sub 1], respectively, both with C[sub 3v] symmetry. From the ZEKE spectra, the adiabatic ionization potentials of the neutral molecules are determined to be 44 730, 41 508, and 42 324 cm-1, and the Cu[sup +]/Cu–X stretching frequencies are 268/199, 214/187, and 188/155 cm-1 for X=N, P, and As, respectively. The degenerate Cu[sup +]/Cu–P–C and Cu[sup +]/Cu–As–C bending frequencies are measured to be 146/83 and 118/52 cm-1, while the Cu[sup +]/Cu–N–C mode was not observed. In addition, the CH[sub 3] wag, X–C stretching, and XC[sub 3] umbrella modes are also measured for the phosphine and arsine complexes. From the MP2 theory, the dissociation energies of the Cu[sup +] and Cu complexes are estimated to be 59/12, 70/15, and 65/11 kcal mol-1 down the X group. Both MP2 and B3LYP predictions of ionic vibrational frequencies compare well with the spectroscopic values, but the B3LYP calculations of neutral low frequency modes are less satisfactory. On the other hand, the B3LYP calculations yield better ionization potentials than the MP2 methods for these molecules. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Aluminum–methylamine complexes are produced in pulsed molecular beams. Their electronic spectra are obtained using threshold photoionization and zero-electron-kinetic-energy photoelectron spectroscopies and interpreted using density functional and ab initio calculations. The photoelectron spectra reveal ground electronic states and intermolecular and ligand-based vibrations of Al–NH[sub n](CH[sub 3])[sub 3-n] and Al[sup +]–NH[sub n](CH[sub 3])[sub 3-n] (n=0–2), adiabatic ionization energies of Al–NH[sub n](CH[sub 3])[sub 3-n], and a low-lying excited electronic state of Al–NH[sub 2]CH[sub 3]. In addition, the spectroscopic measurements and theoretical calculations show strong methyl substitution effects on the ionization energies and metal–ligand binding. Striking spectral differences are discovered between these aluminum complexes and previously studied gallium and indium analogues. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The electronic states of gaseous diatomic NiSi have been investigated using the combined techniques of resonant two-photon ionization spectroscopy, dispersed fluorescence spectroscopy, and density functional computations. A single electronic band system, designated as the [18.0]1←X [SUP1]Σ[SUP+] system, has been found in the 17 500-19 500 cm[SUP-1] range, and three bands of this system have been rotationally resolved and analyzed. To shorter wavelengths, the spectrum becomes much more congested and intense, and four bands in this region have been rotationally resolved and analyzed as well. A dispersed fluorescence investigation has allowed the measurement of 17 vibrational levels of the ground state. Through this work, the ground state of [SUP58]Ni[SUP28]Si is demonstrated to have [SUP1]Σ[SUP+] symmetry, with r[SUB0] = 2.0316(4) Å, ω[SUBe] = 467.43(30) cm[SUP-1], and ω[SUBe]&chi[SUBe] = 2.046(21) cm[SUP-1]. These results are in good agreement with the results of density functional computations performed on the ground state. Comparisons to AlCu and CuSi demonstrate that NiSi has a double bond, while these related molecules are best considered as having a single σ-bond. [ABSTRACT FROM AUTHOR]

The yttrium complexes with one and two dimethyl ethers and their deuterated derivatives are prepared with laser vaporization molecular beam techniques, identified with photoionization time-of-flight mass spectrometry, and investigated with pulsed-field-ionization zero-electronkinetic-energy (ZEKE) photoelectron spectroscopy and ab initio calculations. Adiabatic ionization potentials and yttrium-oxygen stretch and ether-based vibrations are measured for the 1:1 and 1:2 complexes. Fermi interactions are observed from the ZEKE spectra of the 1:1 species. The ground electronic states of the monoligand complexes are determined to be [SUP2]A[SUB2] for the neutral and [SUP1]A[SUB1] for the singly charged positive ion, both in C[SUB2v] symmetry, with yttrium binding to oxygen. The coordination of a second ether forms a diligand complex with a linear oxygen-yttrium-oxygen configuration. This is the first electronic-vibrational spectroscopic study of yttrium-polyatomic molecule complexes and weakly bound metal complexes with two or more polyatomic molecules. [ABSTRACT FROM AUTHOR]

Aluminum-trimethylphosphine and trimethylarsine have been prepared by pulsed laser vaporization. Their electronic spectra have been obtained for the first time, using pulsed field ionization zero electron kinetic energy (ZEKE) photoelectron spectroscopy. The ZEKE spectra reveal the information about adiabatic ionization energies, intermolecular and ligand vibrations, and charge effects on molecular geometries. In coordination with the experimental measurements, density functional theory has been used to calculate equilibrium geometries, vibrational frequencies, and bond dissociation energies for the neutral and ionic complexes. The calculations predict that ionization causes the most significant geometry changes in the Al–P–C or Al–As–C angles, in agreement with the experimental observations. The aluminum ion and atom bind phosphorus more strongly than arsenic in these species. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The gallium complexes were produced in pulsed molecular beams and studied with zero electron kinetic energy (ZEKE) photoelectron spectroscopy. Intermolecular vibrational frequencies and adiabatic ionization potentials (IPs) were obtained from ZEKE spectra. Ground electronic states were identified by combining the ZEKE spectra with quantum chemical and Franck–Condon calculations. Ga–NH[sub 3] has an IP of 40 135 cm-1 and metal-ligand stretching frequencies of 270 cm-1 (ω[sub s][sup +]) in the ion and 161 cm-1 (ν[sub s]) in the neutral. The IP of Ga–NH[sub 2]CH[sub 3] is 39 330 cm-1, and the vibrational frequencies are 93 cm-1 (ν[sub b]) for the Ga–N–C bending, 124 cm-1 (ω[sub b][sup +]) for the Ga[sup +]–N–C bending, and 299 cm-1 (ω[sub s][sup +]) for the Ga[sup +]–N stretching. The strength of the gallium–methylamine binding is stronger than that of the gallium–ammonia. The ground state of Ga–NH[sub 3] is [sup 2]A[sup ′](C[sub s]) and that of Ga[sup +]–NH[sub 3] is [sup 1]A[sub 1](C[sub 3v]). In contrast, Ga–NH[sub 2]CH[sub 3] has two doublets, [sup 2]A[sup ′] and [sup 2]A[sup ″](C[sub s]), with virtually the same energies, whereas Ga[sup +]–NH[sub 2]CH[sub 3] has a [sup 1]A[sup ′](C[sub s]) ground state. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Four states that are derived from the 3d(sub Ni)(super 9), 3d(sub Cu)(super 10)sigma(super 2) manifold are observed by a dispersed fluorescence investigation of the low-lying electronic states of NiCu. The results are based on selection rules and comparison to ab initio and ligand field calculations, and modeled using a matrix Hamiltonian and is applied to spectroscopic molecules of AlNi, NiH, NiCl and NiF.

Reports on a spectroscopic study of the Rydberg states of the yttrium monoxide cation (YO) accessed from particular rotational levels combined with a pulsed field ionization, zero electron kinetic energy (PFI-ZEKE) investigation. View that the channel-coupling mechanism induces an inverse autoionization process sensitive to the electron kinetic energy.

Investigates the spectroscopy of diatomic metallic compound LiCu using resonant two-photon ionization spectroscopy. Description of the experimental apparatus; Results of the experiments conducted; Summary of the findings.

The group 13 metal atoms with the group 15 hydrides are prepared with laser-ablation molecular beam techniques and studied with ab initio calculations, threshold photoionization and zero electron kinetic energy photoelectron spectroscopies. The binding between the metal and ligand is enhanced nearly three to five times through this ionization.

This paper presents pulsed-field ionization, zero electron kinetic energy (ZEKE) photoelectron and threshold photoionization spectra of M-X(CH3)3 (M = Ga, In; X = P, As). The ZEKE spectra exhibit well-resolved vibrational structures. A comparison with B3LYP calculations shows that the spectrum of In-P(CH3)3 arises from the 1A1 ← 2E transition and the spectra of Ga-P(CH3)3 and Ga-As(CH3)3 arise from transitions of a Jahn–Teller distorted doublet state to the 1A1 state. The intensities of the 1A1–2E transition in the indium species are described with the Franck–Condon approximation, while the transitions in the gallium complexes are more complicated due to the dynamic Jahn–Teller effect. The adiabatic ionization potentials of Ga-P(CH3)3, In-P(CH3)3, and Ga-As(CH3)3 are 39 635, 38 930, and 40 322 cm–1, respectively, and the ionization threshold of In-As(CH3)3 is ~39 550 cm–1. The metal–ligand stretching frequencies are 143, 116, and 125 cm–1 for Ga+-P, In+-P, and Ga+-As, respectively, and 96 cm–1 for In-P. The intermolecular bending frequencies are 71, 65, and 42 cm–1 for Ga+-P-C, In+-P-C, and Ga+-As-C, respectively, and 47 cm–1 for In-P-C. In addition, ligand-based vibrational frequencies are determined for the CH3 wag, PC3 and AsC3 umbrella, and P-C stretching vibrations. [ABSTRACT FROM AUTHOR]

Single-photon pulsed field ionization-zero electron kinetic energy photoelectron spectroscopy has been used to study the indium–methylamine complexes. The photoelectron spectra have been assigned using density functional theory and Franck–Condon calculations. The spectral assignments identify the symmetric In[sup +]–N stretch mode for In[sup +]–NH[sub 2]CH[sub 3] (259 cm-1), In[sup +]–NH(CH[sub 3])[sub 2] (200 cm-1), and In[sup +]–N(CH[sub 3])[sub 3] (158 cm-1); In–N stretch for In–N(CH[sub 3])[sub 3] (110 cm-1); In[sup +]–N–C bend for In[sup +]–NH[sub 2]CH[sub 3] (110 cm-1) and In[sup +]–NH(CH[sub 3])[sub 2] (120 cm-1); In–N–C bend for In–NH[sub 2]CH[sub 3] (91 cm-1) and In–NH(CH[sub 3])[sub 2] (106 cm-1); and In[sup +]–N–H bend for In[sup +]–NH(CH[sub 3])[sub 2] (324 cm-1). Methyl substitutions for hydrogen atoms greatly influence the indium–nitrogen stretch forces and ionization potentials of the complexes. The indium–amine binding in these complexes includes orbital interaction and electrostatic forces. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A dispersed fluorescence investigation of the low-lying electronic states of NiCu has allowed the observation of four out of the five states that derive from the 3d(Ni)9 3d(Cu)10 sigma2 manifold. Vibrational levels of the ground X2delta(5/2) state corresponding to v = 0-11 are observed and are fit to provide omega(e) = 275.93 +/- 1.06 cm(-1) and omega(e)x(e) = 1.44 +/- 0.11 cm(-1). The v = 0 levels of the higher lying states deriving from the 3d(Ni)9 3d(Cu)10 sigma2 manifold are located at 912, 1466, and 1734 cm(-1), and these states are assigned to omega values of 3/2, 1/2, and 3/2, respectively. The last of these assignments is based on selection rules and is unequivocal; the first two are based on a comparison to ab initio and ligand field calculations and could conceivably be in error. It is also possible that the v = 0 level of the state found at 912 cm(-1) is not observed, so that T0 for the lowest excited state actually lies near 658 cm(-1). These results are modeled using a matrix Hamiltonian based on the existence of a ground manifold of states deriving from the 3d9 configuration on nickel. This matrix Hamiltonian is also applied to the spectroscopically well-known molecules AlNi, NiH, NiCl, and NiF. The term energies of the 2sigma+, 2pi, and 2delta states of these molecules, which all derive from a 3d9 configuration on the nickel atom, display a clear and understandable trend as a function of the electronegativity of the ligands.