Characterization of a vacuum ultraviolet light source at 118 nm

Abstract

Vacuum ultraviolet (VUV) light at 118 nm has been shown to be a powerful tool to ionize molecules for various gas-phase chemical studies. A convenient table top source of 118 nm light can be produced by frequency tripling 355 nm light from a Nd:YAG laser in xenon gas. This process has a low efficiency, typically producing only nJ/pulse of VUV light. Simple models of the tripling process predict that the power of 118 nm light produced should increase quadratically with increasing xenon pressure. However, experimental 118 nm production has been observed to reach a maximum and then decrease to zero with increasing xenon pressure. Here, we describe the basic theory and experimental setup for producing 118 nm light and a new proposed model for the mechanism limiting the production based on pressure broadened absorption.

Unraveling the Photodissociation Branching and Pathways of Methane at 118 nm by Imaging the CH3, CH2, and CH Fragments

“…A supersonically expanded CH 4 beam at 6 atm (neat) is pulsed and intersected by a VUV laser pulse (width ∼2 ns) at 118 nm. The 118 nm photon (10.48 eV) that serves as both the photolysis and one-photon ionization probe is produced by the third harmonic generation scheme of a third harmonics YAG laser (355 nm) in a Xe cell (∼11 Torr), which consists of a fused silica focusing lens ( f = 15 cm) and a LiF exit window (2 mm thickness). ,, Thus, both 355 and 118 nm lasers are diverged with respective diameters of 7.3 and 4.0 mm when perpendicularly intersecting the CH 4 beam. To minimize the (VUV + UV) background (see details in the Supporting Information), the 355 nm laser energy is kept under 5 mJ/pulse.…”

Visualizing the distribution of curcumin in the root of Curcuma longa via VUV-postionization mass spectrometric imaging

“…In addition, the 355 nm laser that has not been transformed into the 118 nm laser will spread and not focus on the center of the ionization chamber. 37 The VUV (118 nm) laser beam, which was parallel to the corundum sample plate, intercepted the desorption plume. The surface of the sample plate had inconsiderable topography in the Z direction to ensure the focal plane changed very slightly upon scanning the tissue sections.…”

Photodissociation dynamics of tetrahydrofuran at 193 nm

“…After a delay of 20 ns, the neutral photofragments were ionized by the 118.2 nm (10.49 eV) vacuum-ultraviolet (VUV) probe beam, generated by frequency tripling the third harmonic of a Nd:YAG laser (Continuum Surelite I) in a phasematched mixture of 298 mbar Argon (BOC, 99.9%) and 27 mbar Xenon (BOC, 99.9%). [42][43][44][45] The probe laser beam was linearly polarized along the time-of-flight axis (perpendicular to the imaging plane) to ensure that all anisotropy observed in the measured photofragment angular distributions results from the photolysis step. However, preliminary experiments performed with the probe laser polarised either parallel or perpendicular to the imaging plane revealed no differences in the recorded images.…”