H3O + Overtone Spectroscopy

In this report we present preliminary results in search for the H3O + spectra in the first OH stretching overtone region. At least 30 absorption lines of H3O + were found in near infrared region 6900 to 6960 cm 1 using a very sensitive time resolved continuous wave cavity ringdown spectrometer (cw-CRDS) with concentration modulation. H3O + ions were produced in pulsed microwave discharge in He/H2O mixture. A technique based on time resolved absorption has been used to distinguish the absorption lines of short living ions from longer living radicals and water vapors.