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Two resonances in the photodetachment spectrum of H, one just below the n = 3 threshold and the other just below the n =4 threshold, were observed decaying into H {n'=2)+e. The n =3 resonance shows a preference for the n'=2 channel when compared with total-detachment measurements. Fanoline-shape fits give central energies of 12.652+0.003 eV for H * (3) and 13.338+0.004 eV for H **(4). These values are in good agreement with current theoretical calculations. PACS number(s): 32.80.Fb, 31.50.+w, 32.80.Cy

H2S was photodissociated using an ArF excimer laser at 193 nm to form HS photofragments. LIF spectra of HS in the region of 324 nm were obtained using a pressure tuned dye laser with improved resolution of the R1 and RQ21 branches in the A 2Σ+←X 2Π3/2 transition. The zero field linewidths and the Zeeman splitting of the RQ21 (1.5) line in a magnetic field were obtained. The latter was used to verify the g values expected for a Hund’s case (b) 2Σ+ upper state and Hund’s case (a) 2Π lower state. Depolarization of fluorescence in a magnetic field using the RQ21 (3.5) line with σ-polarized LIF excitation was used to determine an estimated lifetime of 0.15–0.3 ns for the lowest vibrational level of the 2Σ+ state. A lower limit on the lifetime of 0.17 ns was determined from the measured adsorption linewidths. No rotational dependence on the linewidth was observed.

The B 1Σ+ state of carbon monoxide was created by a two-photon absorption of 230 nm laser radiation. The B 1Σ+ state was identified by the positions of the Q branch 0–0 absorption band and the vibrational bands of B 1Σ+ → A 1Π fluorescence occurring after excitation. Collision-induced b 3Σ+ → a 3Π emission in the 350 nm region was also observed. The lifetimes of the B 1Σ+ → A 1Π and the b 3Σ+ → a 3Π emission were obtained as well as the self-quenching rate constants and the CO (B 1Σ)) quenching rate by N2. In addition to the two-photon laser induced fluorescence of B 1Σ+ carbon monoxide, a three-photon resonant (2+1) ionization was observed. Laser power dependence studies indicate that ionization of the B 1Σ+ state was nearly saturated at the laser fluence used, implying that most CO (B 1Σ+) was ionized rather than fluorescing. The measured polarization ratios for circularly to linearly polarized excitation of fluorescence and ionization was much larger than the expected values suggesting that other three-photon processes are occurring and occur more efficiently for linear polarization.

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