Absorption lines from molecular hydrogen ($\rm H_2$) in the spectra of background sources are a powerful probe physical conditions intervening cold neutral medium. At high redshift, $z>2$, $\rm H_2$ conveniently shifted optical domain, allowing use ground-based telescopes to perform high-resolution spectroscopy, which is essential for proper analysis gas. We describe recent observational progre...

A simple corrected resonance light-scattering (CRLS) technique was established to correct for any distortion of the resonance light scattering (RLS) spectra resulting from molecular absorption. By using an absorption cell holder to change the propagation direction of the incident light beam of a common spectrofluorometer, the molecular absorption was directly measured through a spectrofluoromet...