Photoelectron spectroscopy of OH−(N2O)n=1–5

Photoelectron Spectroscopy of OH−-Anion–Water Clusters Generated by Ultrasonic Nebulizer

Investigating molecules in the gas phase is the only way to discover their intrinsic molecular properties; however, it is challenging to produce the gaseous phase of large-molecule chemicals. Thermal evaporation is typically used to convert molecules into gases, but it is still challenging to study ionic molecules in solutions in the gas phase. Electrospray ionization is one of the best methods to generate molecules in the gas phase, and it is uniquely capable of studying large biomolecules, including proteins. However, the molecular temperature required to study the spectroscopic properties of the molecules is very high. In this study, we developed a new, simple evaporation method using an ultrasonic nebulizer to obtain gas-phase molecules. Using this new equipment, we observed OH⁻ anions and their water clusters in the gas phase and obtained their photoelectron spectra. We observed that the vertical electron-detachment energy (VDE) of OH⁻ was 1.90 ± 0.05 eV and the VDEs of its water clusters and OH⁻ (H₂O)_n (n = 1–2) decreased to 1.50 ± 0.05 eV (n = 1) and 1.30 ± 0.05 eV (n = 2), respectively.

Photoelectron angular distributions in negative-ion photodetachment from mixed sp states

We describe an approach for constructing analytical models for the energy-dependence of photoelectron angular distributions in the one-electron, non-relativistic approximation. We construct such a model for electron emission from an orbital described as a superposition of s- and p-type functions, using linearly polarized light. In the limits of pure s or pure p electron photodetachment or photoionization, the model correctly reproduces the familiar Cooper-Zare formula. The model predictions are compared to experimental results for strongly solvated H(-) and NH(2)(-), corresponding to predominantly s and predominantly p character parent states, respectively.

Dynamics on the HOCO potential energy surface studied by dissociative photodetachment of HOCO− and DOCO−

An experimental study of the dissociative photodetachment (DPD) dynamics of HOCO(-) and DOCO(-) at a photon energy of 3.21 eV has been carried out to probe the potential energy surface of the HOCO free radical and the dynamics of the OH+CO-->H+CO(2) reaction. These photoelectron-photofragment coincidence experiments allow the identification of photodetachment processes leading to the production of stable HOCO free radicals and both the H+CO(2) and OH+CO dissociation channels on the neutral surface. Isotopic substitution by deuterium in the parent ion is observed to reduce the product branching ratio for the D+CO(2) channel, consistent with tunneling playing a role in this dissociation pathway. Other isotope effects on the detailed partitioning of kinetic energy between photoelectrons and photofragments are also discussed. The results are compared to recent theoretical predictions of this DPD process, and evidence for the involvement of vibrationally excited HOCO(-) anions is discussed.