Valence and Core-Level X-ray Photoelectron Spectroscopy of a Liquid Ammonia Microjet

Abstract

Photoelectron spectroscopy of microjets expanded into vacuum allows access to orbital energies for solute or solvent molecules in the liquid phase. Microjets of water, acetonitrile and alcohols have previously been studied; however, it has been unclear whether jets of low temperature molecular solvents could be realized. Here we demonstrate a stable 20 μm jet of liquid ammonia (−60 °C) in a vacuum, which we use to record both valence and core-level band photoelectron spectra using soft X-ray synchrotron radiation. Significant shifts from isolated ammonia in the gas-phase are observed, as is the liquid-phase photoelectron angular anisotropy. Comparisons with spectra of ammonia in clusters and the solid phase, as well as spectra for water in various phases potentially reveal how hydrogen bonding is reflected in the condensed phase electronic structure.

Effective one-particle energies from generalized Kohn–Sham random phase approximation: A direct approach for computing and analyzing core ionization energies

“…was in close agreement with the experiment indicating that the CVS-ADC(4) is a reliable benchmark for CEBEs of these tautomers.For all three tautomers, we find that the d-GKS-spRPA based C(1s) CEBEs are within 0.2 eV of CVS-ADC(4) values. Unlike the case of ammonia clusters, here we find that V C,s component is crucial for reducing relative errors in CEBEs and MAE errors in chemical shifts, seeFig.…”

“…1 Experimentally, molecular CEBEs are accessible by X-ray photoelectron spectroscopy (XPS); recent advances in high vapor pressure liquid-jet experiments have extended the scope of XPS measurements to solvents such as water and ammonia. [2][3][4] Chemical shifts of solvated molecules in liquid water provide important clues for concentration profiles near the vapor-liquid interface. [5][6][7][8] Ab initio calculation of core ionization potentials provides a means to predict CEBEs and rationalize chemical shifts.…”

Deeply cooled and temperature controlled microjets: Liquid ammonia solutions released into vacuum for analysis by photoelectron spectroscopy

“…In our previous work on PES of liquid ammonia, [35] we maintained the temperature of the reservoir roughly within the required temperature regime by filling liquid nitrogen into the ethanol bath once the temperature began to rise (Fig. 1).…”

“…Spectra are displayed such that the 3a 1 liquid peak is at 9.09 eV. [35] In addition, the intensity of the 3a 1 liquid peak is displayed to yield the same peak height.…”

“…[33,34] By developing a device to create a liquid ammonia microjet in vacuum, we recently enabled the respective liquid phase PES studies of ammonia. [35] The purpose of the present manuscript is to describe two versions of the experimen-tal setup with focus on temperature control and suitability for various solutes which is presented in section II. We conclude by showing representative valence PE spectra from the neat solvent at several distinct temperatures as well as from iodide salts dissolved in liquid ammonia.…”