Laser absorption spectroscopy of LaF: Analysis of the B{sup 1}{Pi}-X{sup 1}{Sigma}{sup +} transition
- Emory Univ., Atlanta, GA (United States)
Laser absorption spectrum of the LaF B{sup 1}{Pi}-X{sup 1}{Sigma}{sup +} (2,0), (1,0), (2,1), and (3,2) bands was recorded. Gas phase LaF was obtained by heating a mixture of a 0.2 g of La metal and 0.3 g of LaF{sup 3} powder to 1900 K. In order to modulate the absorption signal, the concentration of LaF was varied by passing a 25 kHz discharge (80-100W, 0.5A peak current) through the vapor. Under these conditions the tantalum heating tube used to vaporize the sample also acted as a hollow cathode. The B-X band system was observed previously. In analyzing the spectrum, the authors have combined absorption data with that from the Reference. Accurate molecular constants (in cm{sup -1}) and internuclear distance r{sub e} (in nm) for the X{sup 1}{Sigma}{sup +} state are: {omega}{sub e} = 573.318, {omega}{sub e}x{sub e} = 2.18, B{sub e} = 0.246411(15), {alpha}{sub e} = 1.251(15) x 10{sup -3}, r{sub e} = 0.20232. Rotational perturbations were evident in the B{sup 1}{Pi} {upsilon}{prime} =1,{upsilon}{prime} =2,and {upsilon}{prime}=3 levels. The pattern of the B{sup 1}{Pi} state perturbations was shown to be a consequence of the interaction with the c{sub 1}{sup 3}{Delta}{sub 1} state by using the experimental value of {omega}{sub e} =450 cm{sup -1} and estimated value of {omega}{sub e}x{sub e} =3.5 cm{sup -1} for the triplet state. The principal new results to emerge from this investigation are the determination of the equilibrium constants for the B{sup 1}{Pi} and X{sup 1}{Sigma}{sup +} states of LaF.
- OSTI ID:
- 437227
- Report Number(s):
- CONF-9606118--; CNN: Grant F19628-90-C-025
- Country of Publication:
- United States
- Language:
- English
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