Direct observation of transient fluorine atoms with 25-[mu]m wavelength-stabilized diode laser absorption
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)
Through the use of continuous diode laser absorption, detection of transient fluorine atoms with an initial number density in the range of 10[sup 14] cm[sup [minus]3] has been demonstrated. A crucial part of the continuous-detection technique was laser frequency stabilization with a reference cell of atomic fluorine with Zeeman modulation of the absorption lines to generate a feedback signal. Long-term wavelength stability was demonstrated with second-harmonic phase-sensitive detection of the second-derivative signal for periods up to several hours. For determination of the short-term wavelength stability in the range of microseconds to seconds, a transient signal was generated by photolysis of F[sub 2] with an excimer laser at 308 nm. The initial diode laser absorption was compared to a calculated value obtained from the measured excimer laser fluence, the known dissociation cross section of F[sub 2], and the atomic fluorine absorption cross section, which included a statistical population distribution, the finite bandwidth of the laser diode, and the effects of pressure broadening. The observed absorption was approximately 33% less than the calculated value, possibly because of the diode laser's wavelength instability on the time scale of a few seconds, which is consistent with an observed amplitude instability from pulse to pulse when pulsed at 1--10 Hz.
- OSTI ID:
- 7049823
- Journal Information:
- Applied Optics; (United States), Vol. 33:15; ISSN 0003-6935
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FLUORINE
ABSORPTION SPECTRA
ATOMS
LASER SPECTROSCOPY
LOW PRESSURE
P STATES
PRESSURE DEPENDENCE
SOLID STATE LASERS
TRANSIENTS
ELEMENTS
ENERGY LEVELS
HALOGENS
LASERS
NONMETALS
SPECTRA
SPECTROSCOPY
664200* - Spectra of Atoms & Molecules & their Interactions with Photons- (1992-)