Concentration Modulation Spectroscopy With a Pulsed Slit Supersonic Discharge Expansion Source

Published

August 1, 2001

Author(s)

S Davis, M Farnik, D Uy, David Nesbitt

Abstract

Frequency modulated discharges are combined with pulsed slit supersonic expansions to provide an intense, long path source of jet-cooled radicals/molecular ions for direct absorption laser spectroscopy. The high modulation frequency (100 kHz) permits lock-in detection of the modulated absorbance signals at sensitivities down to 7.3 x 10^-7absorbance/Hz^1/2 (within 40% of the shot noise limit) and provides excellent discrimination for radical or molecular ion spectra in the presence of much higher precusor concentrations. The sensitivity of these methods is demonstrated with direct absorption spectral data on sample jet-cooled molecular ions (H⁺₃) and hydrocarbon radicals (CH₃CH₂).

Citation

Chemical Physics Letters

Volume

344

Issue

No. 1-2

Pub Type

Journals

Keywords

absorbance signals, direct absorption laser spectroscopy, Frequency modulated discharges

Citation

Davis, S. , Farnik, M. , Uy, D. and Nesbitt, D. (2001), Concentration Modulation Spectroscopy With a Pulsed Slit Supersonic Discharge Expansion Source, Chemical Physics Letters (Accessed October 9, 2025)