Interaction of photons with molecules - cross-sections for photoabsorption, photoionization, and photodissociation

Abstract

A survey is given of recent progress in measurements of photoabsorption, photoionization, and photodissociation cross-sections of molecules in the wavelength range of photons in the vacuum ultraviolet (VUV), where the optical oscillator-strengths of most molecules are predominantly distributed. Some remarks are presented on molecules in the condensed phase. Particular emphasis is placed on the current understanding of spectroscopy and dissociation dynamics of molecules in the superexcited states which are produced through the interaction of photons in this wavelength range. In the VUV range, most of the observed super-excited states are assigned to high-Rydberg states which are vibrationally (and/or rotationally), doubly, or inner-core excited, and converge to each of the ion states.

Rapid Identification and Quantification of Linear Olefin Isomers by Online Ozonolysis-Single Photon Ionization Time-of-Flight Mass Spectrometry

“…SPI mass spectra of seven involved aldehydes except formaldehyde (IE= 10.88 eV), as its IE is higher than the photon energy and it cannot be ionized by SPI, are shown in Figure 2. The fragment ions observed in the SPI mass spectra of the investigated aldehydes were attributed to neutral dissociation process that was discussed in depth by Hatano, Zimmerman, and coworkers [37][38][39] and displayed in Supporting Information Figure S1. Figure 2 demonstrates that neutral dissociation of the aldehyde molecules is the dominant SPI ionization channel for all aldehydes as they exhibit distinct fragment ions.…”

Assessment of Single-Photon Ionization Mass Spectrometry for Online Monitoring of in Vitro Aerosol Exposure Experiments

“…The given signal for each substance at a certain concentration can be related to the signal of a reference substance at the same concentration. Thus, the signal ratio between the targeted and reference substances is calculated as the calibration factor, often termed cross-section, between the two substances . We used toluene as the reference substance at a concentration of 100 ppm.…”

“…Thus, the signal ratio between the targeted and reference substances is calculated as the calibration factor, often termed cross-section, between the two substances. 8 We used toluene as the reference substance at a concentration of 100 ppm.…”

Investigation of the Photoionization Properties of Pharmaceutically Relevant Substances by Resonance-Enhanced Multiphoton Ionization Spectroscopy and Single-Photon Ionization Spectroscopy Using Synchrotron Radiation

“…For the first part of the measurements single-photon ionization (SPI) was utilized. 16–18 The neutral molecule can be ionized if the energy of one single vacuum-ultraviolet (VUV) photon (λ < 200 nm) is equal or higher than the ionization energy of the investigated substance. There are different possibilities to generate the required VUV-photons, e.g., F 2 lasers (157 nm), synchrotron radiation, or the frequency-tripled third harmonic generation of Nd:YAG lasers.…”