The Tunable, Narrow-Bandwidth Excimer Laser, the New Workhorse for Photochemistry in the UV and VUV

Excimer lasers are powerful sources of radiation in the UV, providing several laser lines between 157 and 353 nm. The excimer laser transition is bound-free, and thus the emitted wavelengths are broad-band (up to 200 cm−1). In addition the high gain (0.15 cm−1) of the laser gas causes a rather large divergence (>1 mrad) in conventional excimer lasers.A new excimer laser concept is described which improves the spectral brightness in terms of watt/(rad × bandwidth) by three orders of magnitude. This allows, through non-linear processes such as Raman shifting the fundamental output and four-wave-mixing in gases, the generation of new laser lines in the UV and VUV.