1.9 fs deep-UV pulses from third-harmonic generation in argon

Generation of few-femtosecond (fs) pulses in the ultraviolet (UV) is important in ultrafast spectroscopy since several bio-relevant molecules, including DNA bases, possess electronic transitions in this spectral region [1]. Exploiting nonlinear processes driven by intense laser pulses has led to several advances to meet this challenge. We developed a source delivering 1.9 fs (2.2 cycles at 255 nm) deep-UV pulses with 150 nJ of energy on target [2].