Open AccessResonance-enhanced, rare-gas-assisted femtosecond-laser electronic-excitation tagging in argon/nitrogen mixtures
Author(s) -
Stephen W. Grib,
Hans U. Stauffer,
Sukesh Roy,
Stephen A. Schumaker
Publication year - 2021
Publication title -
applied optics
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 197
eISSN - 2155-3165
pISSN - 1559-128X
DOI - 10.1364/ao.419125
Subject(s) - argon , excited state , femtosecond , excitation , materials science , resonance (particle physics) , laser , atomic physics , analytical chemistry (journal) , physics , chemistry , optics , quantum mechanics , chromatography
Multiphoton-resonance enhancement of a rare-gas-assisted nitrogen femtosecond-laser electronic-excitation-tagging (FLEET) signal is demonstrated. The FLEET signal is ideal for velocimetric tracking of nitrogen gas in flow environments by virtue of its long-lived nature. By tuning to three-photon-resonant transitions of argon, energy can be more efficiently deposited into the mixture, thereby producing a stronger and longer-lived FLEET signal following subsequent efficient energy transfer from excited-state argon to the C ( 3 Π u ) excited state of nitrogen. Such resonant excitation exhibits as much as an order of magnitude increase in this rare-gas-assisted FLEET signal, compared to near-resonance excitation of seeded argon demonstrated in previous work, while reducing the required input excitation-pulse energies by two orders of magnitude compared to traditional FLEET.