Stuart D. Gamblin

Metal Kβ X-ray emission spectra of first row transition metal compounds

Abstract A large body of first row transition Kβ X-ray emission spectra are presented and the splitting of the Kβ peak into Kβ′ and Kβ1,3 is quantified by a consistent curvefitting procedure. Broad trends in the Kβ′:Kβ1,3 intensity ratio are identified and related to the oxidation state of the metal and its chemical environment. Implications for the development of X-ray emission spectroscopy as a tool for chemical speciation are considered.

Further investigations of the Ã←X̃ transition of the Kr·NO and Xe·NO complexes using (1+1) REMPI spectroscopy

Abstract The A←X transitions of the Kr·NO and Xe·NO molecular complexes have been recorded with improved quality. In both cases the origin band consists of a single feature, consistent with a (near) linear A state. The spectra demonstrate a wealth of structure, which increases in complexity to higher energy; this is interpreted in terms of a weakening of the interaction as the internal energy increases. Dissociation energies for both the X and A states are derived. Attempts to record the corresponding spectra for Ne·NO were unsuccessful. The trend in the binding energies in the X and A states of Rg·NO (Rg=He–Xe) is discussed.

The à 2Σ+ state of Ar⋅NO

The  2Σ+ state of Ar⋅NO is studied using (1+1) resonance-enhanced multiphoton ionization (REMPI) spectroscopy. Higher quality spectra than obtained in other studies allow the identification of a number of previously unreported features. The spectrum is analyzed using two models: a rigid van der Waals complex in which NO is weakly bonded to Ar; and a complex in which the free internal rotation of NO is hindered by the anisotropy caused by the presence of the Ar atom. It is concluded that as the intermolecular stretch is excited, then the anisotropy decreases, and the angular motion of the complex becomes more and more like that of a free rotor. Near the origin, the complex has an average geometry approaching linear, whereas when the intermolecular stretch is excited, an average geometry closer to T-shaped occurs; however, when the anisotropy is small, the concept of geometry becomes ill-defined.

Study of the OH and OD radicals with photoelectron spectroscopy using synchrotron radiation

Photoionization of the OH and OD radicals, produced from the H+NO2 and D+NO2 reactions, has been studied in the gas phase in the photon energy region 13.0–17.0 eV using constant ionic state (CIS) and photoelectron spectroscopy (PES) employing synchrotron radiation. Structure in the CIS spectra, recorded for the first and second photoelectron bands, has been assigned to excitation to (a 1Δ,3d) and (A 3Π,3d) Rydberg states. A comparison of vibrationally specific OH and OD CIS spectra, and photoelectron spectra recorded at resonant wavelengths, has allowed a more complete assignment of structure observed in earlier photoionization mass spectrometric measurements. These assignments have been supported by the results of Franck–Condon calculations. The CIS spectra have been shown to be dominated by structure arising from excitation from the outermost valence molecular orbitals of OH [the nonbonding 1π(O 2p) orbital and the bonding 3σ orbital] to O nd Rydberg orbitals. Photoelectron spectra recorded for the firs...

The Ã←X̃(1+1)REMPI spectrum and high-level ab initio calculations of the complex between NO and N2

The results of two separate studies of the complex between NO and N2 are reported. The (1+1) REMPI spectrum of the A←X transition of the complex between NO and N2 is presented of improved quality over that reported previously, and the appearance of the spectrum is discussed. The results of high-level ab initio calculations [RCCSD(T)/aug-cc-pVQZ//QCISD/6-311+G(2d)] on the X 2Π state are also reported. The indications are that the NO moiety is more freely rotating in the complex than is N2, and that a wide angular space is sampled in the zero-point energy level. The appearance of the REMPI spectrum suggests that the A 2Σ+ state is (close to) linear, and RCCSD(T)//QCISD calculations on the A state, using Rydberg-function-augmented basis sets, suggest that the lowest energy linear isomer is the ON⋅N2 linear orientation. It is clear, however, that the understanding of this complex, and its spectroscopy, is far from complete, and will be challenging.

A study of the SO molecule with photoelectron spectroscopy using synchrotron radiation

The SO molecule has been studied by photoelectron spectroscopy using vacuum ultraviolet radiation from a synchrotron as the photon source. Both constant ionic state (CIS) and photoelectron spectra have been recorded. Resonances which appear in the CIS spectra recorded for selected vibrational levels of SO+ X 2Π in the photon energy region hν=11.5–15.0 eV have been assigned to excitations to Rydberg states which converge to the SO+ a 4Π and A 2Π states and autoionize to SO+ X 2Π. Also, resonances which appear in the CIS spectra recorded in the photon energy region 15.0–16.4 eV for selected vibrational levels of SO+ b 4Σ− have been assigned to excitations to Rydberg states which converge to SO+ B 2Σ− and autoionize to SO+ b 4Σ−. Photoelectron spectra recorded at selected resonant photon wavelengths show that autoionization can dramatically alter the intensities of the vibrational components in a photoelectron band and may allow extra vibrational structure to be observed. The additional information obtained ...

A study of the BrO and BrO2 radicals with vacuum ultraviolet photoelectron spectroscopy

The BrO radical, prepared by the Br+O3 reaction, has been investigated by ultraviolet photoelectron spectroscopy. Two vibrationally resolved bands were observed corresponding to the ionizations BrO+(X 3Σ−)←BrO(X 2Π) and BrO+(a 1Δ)←BrO(X 2Π). These assignments are supported by the results of complete active space self-consistent field/multireference configuration interaction (CASSCF/MRCI) calculations performed as part of this work. The adiabatic ionization energies of these bands were measured as (10.46±0.02) and (11.21±0.02)eV, respectively. Measurement of the vibrational separations in these bands led to estimates of the vibrational constants in the ionic states of (840±30) cm−1 and (880±30) cm−1, and Franck–Condon simulations of the vibrational envelopes gave values of the ionic state bond lengths of (1.635±0.005) and (1.641±0.005) A for the X 3Σ− and a 1Δ states of BrO+, respectively. The O+Br2 reaction was found to give a band at (10.26±0.02) eV associated with a reaction product. Comparison of the r...

Photoelectron spectroscopy of short-lived molecules using synchrotron radiation

In this paper, examples are given of recent measurements made at the Daresbury Synchrotron Radiation Source on four short-lived diatomic molecules. The equipment designed to overcome the difficulties of interfacing reactive species with the ultra-high vacuum environment of a synchrotron radiation source is described. The measurements presented have been selected to show the advantage of using a continuum source of radiation in identifying new structure in the photoionization continuum of these molecules.

A theoretical study of the ligand-exchange reactions of Na+ X complexes (X = O, O2, N2, CO2 and H2O): implications for the upper atmosphere

This article has been retracted at the request of the editor. Reason: The publisher regrets that several errors appeared in this paper and that it therefore has been retracted. A correct version of the complete paper has been published in Volume 64, Issue 7, pages 863–870 of the Journal of Atmospheric and Solar-Terrestrial Physics.

The interaction energies of the Rg·NO+ cationic complexes: Rn·NO+

Abstract The equilibrium geometry and harmonic vibrational frequencies of Rn·NO + are calculated at the QCISD level of theory, employing an effective core potential augmented by a large, flexible diffuse and polarization valence space. The interaction energy is then calculated at the CCSD(T) level using a larger basis set based on a different ECP. The trends in the bonding in the Rg·NO + complexes (Rg=rare gas) are then noted, and it is confirmed that the major interaction in these species is the charge/induced-dipole interaction.