Doppler-Free Two-Photon Excitation Spectroscopy and the Zeeman Effect in the “Channel Three” Region of C6H6

Abstract

Doppler-free two-photon excitation spectra and the Zeeman effects for the 1021401 and 1011401 bands, whose vibrational excess energies are 3412 and 2492 cm−1, respectively, of the S11B2u ← S01A1g transition in gaseous benzene-h6 have been measured. Rotationally resolved lines up to a rotational excess energy of 945 cm−1 in the 1011401 band, whose excess energy is isoenergetic with the one of the 1021401 band at low J, have been observed. The density of perturbation is observed to increase around the K = 0 and K = J levels in the 1011401 band as the rotational energy increases, but line broadening is not observed. It was reported that only the K = 0 lines at low J and the K = J lines at high J were observed as a sharp line and the rest was washed out by broadening in the 1021401 band. The assignments are confirmed by the Zeeman spectra. The character and magnitude of Zeeman splittings in both bands could be understood as originating from the electronic orbital angular momentum arising from a mixing of the S11B2u and S21B1u states via J–L coupling. The levels of the S11B2u state are found not to be mixed with a triplet state by the Zeeman effect.

Sub-Doppler high-resolution excitation spectroscopy of the S1←S0 transition of dibenzofuran

“…It suggests that the contribution from the triplet state is negligibly small in the isolated dibenzofuran molecule. It is also similar to the isolated benzene or naphthalene molecules [7][8][9][10][11].…”

“…In contrast with this, irregular energy shifts by local perturbations by other vibrational levels in the same electronic state are seen in higher vibrational levels in benzene or naphthalene molecules [7][8][9][10][11]. It is desired to extend the measurement and analysis for higher vibrational levels.…”

“…It is of great importance to investigate the molecular structure and the excited state dynamics. Ultrahigh-resolution laser spectroscopy is very powerful to accurately study the molecular structure and dynamical processes in the electronic excited state such as internal conversion (IC), intersystem crossing (ISC), and intramolecular vibrational redistribution (IVR) [2][3][4][5][6][7][8][9][10][11]. We have already studied sub-Doppler electronic spectrum of dibenzo-p-dioxin [12] and found that this molecule is bent out-of-plane and predissociating in the S 1 1 B 1u state.…”

Jet spectroscopy of buckybowl: Electronic and vibrational structures in the S and S1 states of triphenylene and sumanene

“…It has been shown by high-resolution spectroscopy that this is attributed to internal conversion (IC) assisted by intramolecular vibrational redistribution (IVR) due to the Coriolis interaction at high vibrational levels in the S 1 1 B 2u state. 23,24 Intersystem crossing (ISC) to the triplet state is considered to be very slow for planar aromatic hydrocarbons. 25,26 The mechanism of the deuterium effect in channel three has not yet been identified.…”

High-resolution spectroscopy of weak and short-lived bands of the S1 B13u←S A1g transition of naphthalene

“…11 However, in contrast with benzene, the fluorescence quantum yield is not significantly decreased with excess energy up to the S 2 1 B 2u ← S 0 1 A g region. [15][16][17] The rotationally resolved high-resolution spectra of the S 1 1 B 3u ← S 0 1 A g transition were first observed by Meerts and co-worker. 18 They also observed the high-resolution spectra by sensitized phosphorescence detection 19 and the results show that ISC process occurs in the S 1 state.…”