Masao Kakimoto

Doppler-limited dye laser excitation spectroscopy of the HSO radical

Abstract The cw dye laser excitation spectrum of the A 2 A′(003) ← X 2 A″(000) vibronic transition of the HSO radical was observed between 16 420 and 16 520 cm−1 with Doppler-limited resolution, 0.03 cm−1. The HSO radical was produced by reaction of discharged oxygen with H2S or CH3SH. The observed spectra were assigned to 751 transitions of the K′a ← K″a = 2 ← 3, 1 ← 2, 0 ← 1, 1 ← 0, 2 ← 1, and 3 ← 2 subbands, and were analyzed to determine rotational constants, centrifugal distortion constants, and spin-rotation interaction constants with good precision. The signs of the spin-rotation interaction constants were determined for both the upper and the lower state from the observed spectra. The band origin obtained is 16 483.0252 (2.5σ = 0.0013) cm−1. The molecular constants which were determined reproduce the observed transitions with an average deviation of 0.0045 cm−1.

Doppler-limited dye laser excitation spectroscopy of the CCN radical

The cw dye laser excitation spectrum of the A2Δ(000) ← X2Π(000) vibronic transition of the CCN radical was observed between 21 205 and 21 335 cm−1 with the Doppler-limited resolution, 0.04 cm−1. The CCN radical was produced by reaction of microwave discharged CF4 with CH3CN. The observed spectrum was analyzed to determine rotational and centrifugal constants and effective spin-orbit and spin-rotation coupling constants for both the A2Δ(000) and the X2Π(000) states, and also the Λ-type doubling constants for the X2Π(000) state. The constants determined reproduce the observed spectrum with an average deviation of 0.0027 cm−1, and are considered to be precise enough for predicting the ground-state microwave transition frequencies. No evidence was found for perturbation in either the A2Δ(000) or the X2Π(000) state.

Doppler-limited dye laser excitation spectroscopy of HCCl

Abstract The dye laser excitation spectrum of the A 1 A″(000)- X 1 A′(000) vibronic transition of DCF was observed between 17 200 and 17 400 cm −1 with the Doppler-limited resolution. DCF was produced by the reaction of microwave-discharged CF 4 with CD 3 F. The observed spectra, which were found to be nearly free of perturbations, were assigned to 858 transitions of the K ′ a − K ″ a = 4−5, 3−4, 2−3, 1−2, 0−1, 1−0, 2−1, 3−2, 3−3, 2−2, 1−1, 0−0, 2−0, and 0−2 subbands, and were analyzed to determine the rotational constants and centrifugal distortion constants for both the X and A states. The rotational constants of DCF thus determined were combined with those of HCF to calculate the structural parameters for this molecule: r( CH ) = 1.138 A , r( CF ) = 1.305 A , and ∠HCF = 104.1° for the ground X state, and r( CH ) = 1.063 A , r( CF ) = 1.308 A , and ∠HCF = 123.8° for the excited A state.

Doppler-limited dye laser excitation spectroscopy of the DSO radical

Abstract The A 2 A′(003) ← X 2 A″(000) vibronic transition (16 370 to 16 425 cm −1 ) of the DSO radical in studied by Doppler-limited dye laser excitation spectroscopy. DSO is produced in a flow system by reacting the products of a microwave discharge in O 2 with D 2 S. About 637 observed lines are assigned to 987 transitions of the 19 subbands: K ′ a ← K ″ a = 6 ← 5, 5 ← 4, 4 ← 3, 3 ← 2, 2 ← 1, 1 ← 0, 0 ← 1, 1 ← 2, 2 ← 3, 3 ← 4, 0 ← 0, 1 ← 1, 2 ← 2, 3 ← 3, 4 ← 4, 3 ← 1, 2 ← 0, 0 ← 2, and 1 ← 3. They are analyzed to determine rotational constants, centrifugal distortion constants, and spin-rotation constants for both the ground and the excited electronic states. The band origin obtained is 16 413.874 (2.5σ = 0.002) cm −1 . The rotational constants determined are combined with the previous result on HSO (M. Kakimoto et al., J. Mol. Spectrosc. 80, 334–350 (1980)) to calculate the structural parameters for this radical in both the states: r( SO ) = 1.494(5) A , r( SH ) = 1.389(5) A , and ∠HSO = 106.6(5)° for the X 2 A″ state, and r( SO ) = 1.661(10) A , r( SH ) = 1.342(8) A , and ∠HSO = 95.7(21)° for the A 2 A′(003) state, where values in parentheses denote 2.5σ.

High-resolution optogalvanic study of the c4(0)1Πu, c′5(0)1Σu+, and a″(0)1Σg+ Rydberg states of N2

Abstract A new optogalvanic technique with an rf discharge was applied to a high-resolution study of the Rydberg states of N 2 . The Ledbetter band, c 4 (0) 1 Π u ← a ″(0) 1 Σ g + , and a new visible band, c ′ 5 (0) 1 Σ u + ← a ″(0) 1 Σ g + , were studied at a Doppler-limited resolution of 0.05 cm −1 . A Doppler-free method was also applied to resolve overlapped lines. Precise wavenumbers were determined for the rotational transitions of the two Rydberg bands. The rotational and the centrifugal constants for the lowest Rydberg state, a ″(0) 1 Σ g + , were determined to be B 0 = 1.913748(42) cm −1 and D 0 = 6.088(99) × 10 −6 cm −1 , where the numbers in parentheses are the standard deviation and apply to the last digits.

Infrared–optical double resonance spectroscopy of the NH2 radical

Vibration‐rotation transitions of NH2 in the A 2A1 state were observed with sub‐Doppler resolution, by using a Rh 6G dye laser and a CO2/N2O laser combined with the laser magnetic resonance technique. When the dye laser pumped the A 2A1 (0,9,0) 220←X 2B1(0,0,0) 110 transition, 39 MJ components of (0,10,0) 211←(0,9,0) 220, and 5 MJ components of (0,10,0) 111←(0,9,0) 220 in A were observed by sweeping the magnetic field. Four additional lines which corresponded to changes in fluorescence intensity opposite in sign to those for the transitions mentioned above, were also observed and assigned to transitions from A 2A1(0,9,0) to a highly excited vibrational state of X (“u’’ level). The rotational quantum numbers N and J and the spin splitting of the u level were determined as well as the interaction term between the u and A (0,10,0) 211 states. The u level is tentatively assigned to a rotational level in X(2,8,0), however, the observed spin splitting does not agree with that for X(0,8,0) calculated by Jung...

Microwave optical double resonance of HNO: Rotational spectrum in Ã1A′′(100).

Rotational transitions in the ?1A″(100) state of HNO were observed using the technique of microwave optical double resonance. The HNO molecule was produced in a fast flow system by the reaction of discharged oxygen with a mixture of propylene and NO. Eighteen rotational lines observed in the frequency regions of 8 to 157 GHz and rf were analyzed to give rotational constants and centrifugal distortion constants. Perturbations were found in the K‐type doubling frequencies of K−1 =1 and 2.

Hyperfine structure of the PH2 radical in X̃2B1 and Ã2A1 from intermodulated fluorescence spectroscopy

Abstract The PH 2 radical was generated in a flow system by the reaction of red phosphorus with microwave discharge products of hydrogen. The hyperfine structures of 12 I H = 0 and 14 I H = 1 rotational lines of the A 2 A 1 (000) ← X 2 B 1 (000) vibronic band were observed by the method of intermodulated fluorescence; a cw dye laser was employed as a source and the resolution of about 10 MHz was achieved. The observed spectra were analyzed by taking into account the Fermi contact and the magnetic dipole-dipole interactions of both 31 P and 1 H nuclei. By fixing the ground-state parameters to the recent microwave results, the hyperfine coupling constants were determined for the A 2 A 1 state: a c = 1 747.2(14), T aa = −259.5(38), and T bb = 477.4(34) MHz for 31 P and a c = 190.06(69), T aa = 12.3(16), and T bb = −4.0(32) MHz for 1 H, with the standard error in parentheses. The 31 P nuclear spin-rotation interaction was necessary to be taken into account in the A state as well as in the X state.

Doppler-limited dye laser excitation spectroscopy of the PH2 radical: the Ã2A1(000)X̃2B1(000) band

Abstract The cw dye laser excitation spectrum of the A 2 A 1 (000) ← X 2 B 1 (000) vibronic transition of the PH2 radical was observed between 18 158 and 18 443 cm−1 at Doppler-limited resolution. The PH2 radical was produced by the reaction of discharged hydrogen with powdered red phosphorus. About 1000 lines were observed for Ka up to 7 and N up to 9. Using the ground-state parameters reported by Endo et al. [Y. Endo, S. Saito and E. Hirota, J. Mol. Spectrosc., 97 (1983) 204–212], upper-state term values were calculated from the observed transition frequencies and were subjected to a least-squares analysis to derive rotational constants, centrifugal distortion constants, and spin-rotation interaction constants in the A state. The perturbations observed for the upper state are briefly discussed.