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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]

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.

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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]