THE APPLICATION OF A VUV FOURIER-TRANSFORM SPECTROMETER AND SYNCHROTRON-RADIATION SOURCE TO MEASUREMENTS OF - I - THE BETA(9,0) BAND OF NO

State-of-the-art models of the vacuum ultraviolet (VUV) absorbing prop erties of the atmosphere call for absorption cross sections with detai l on the scale of the Doppler widths. As a consequence, spectroscopic data at resolving powers of the order of 10(6) are needed. To meet the se requirements in the vacuum ultraviolet region, we have used the VUV Fourier transform spectrometer from Imperial College, London, at the synchrotron radiation facility at Photon Factory, KEK, Japan, to measu re photoabsorption cross sections of NO from 195 to 160 nm; and of O-2 from 185 to 175 rrm. The analysis of the beta(9,0) band (B (2)Pi(r),- X-(2)Pi(r),) Of NO provides accurate rotational line positions and te rm values. Molecular constants of the-B(9) (2)Pi level-are T-0=54 205. 097+/-.0.012-cm(-1), A =45.320+/- 0.021 cm(-1), B-v= 1.016 72+/- 0.000 16 cm(-1), D-v(10.61+/- 0.32) X 10(-6) cm(-1), and AD = 0.001 22 +/- 0.000 11 cm(-1). The rotational line strengths and the branching ratio s are also presented. The band oscillator strength is obtained as f = 2.65 x 10(-4) . (C) 1998 American Institute of Physics. [S0021-9606(98 )01529-3] :