Subpicosecond population decay time of the first excited singlet state of thioxanthione in fluid solution

Tittelbach-Helmrich, Dietrich; Steer, Ronald P.

doi:10.1016/0009-2614(96)01081-0

Cited by 17 publications

(10 citation statements)

References 23 publications

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“…2, the SP range of this short‐wavelength emission coincides with the S 0 → S 1 absorption band, which means that it is not the fluorescence from the S 1 state. It should be mentioned that the attempts to observe the prompt emission from the S 1 state in the case of aromatic and aliphatic thioketones have been hitherto unsuccessful because of the extremely short lifetime of this state (∼1 ps) (30) and a low value of the radiative rate constant ( k f ∼ 10 5 s –1 ) (10–12). On the other hand, for many aromatic and aliphatic thioketones, the room temperature fluorescence from the S 2 state and phosphorescence from the T 1 state have been observed (10–12,15–17).…”

Section: Resultsmentioning

confidence: 99%

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Taras-Goślińska

Wenska

Skalski

et al. 2007

Photochemistry and Photobiology

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Intramolecular processes of deactivation of 1,3‐dimethyl‐4‐thiouracil (DMTU) from the second excited singlet (S2) (π, π*) and the lowest excited triplet (T1) (π, π*) states have been studied using perfluoro‐1,3‐dimethylcyclohexane (PFDMCH) as a solvent. The spectral and photophysical (PP) properties of DMTU in CCl4, hexane and water have also been described. For the first time, the fluorescence from S2 state DMTU has been observed. The picosecond lifetime of DMTU in the S2 state (τ S 2) in PFDMCH has been proposed to be determined by a very fast intramolecular reversible process of hydrogen abstraction from the ortho methyl group by the thiocarbonyl group. The shortening of τ S 2 in CCl4 is interpreted to be caused by the intermolecular interactions between DMTU (S2) and the solvent. Results of the phosphorescence decay as a function of DMTU concentration were analyzed using the Stern–Volmer formalism, which enabled determination of the intrinsic lifetime of the T1 state (τ0 T 1) and rate constants of self‐quenching (ksq). The lifetimes, τ0 T 1, of DMTU in PFDMCH and CCl4 are much longer than the values hitherto obtained in more reactive solvents. The PP properties of DMTU both in the S2 and T1 states have been shown to be determined by the thiocarbonyl group.

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Section: Resultsmentioning

confidence: 99%

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Taras-Goślińska

Wenska

Skalski

et al. 2007

Photochemistry and Photobiology

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“…Scheme 1 summarises the deactivation pathways of the BPT S 2 state in acetonitrile. The deactivation of the S 2 state to S 1 is followed instantaneously by efficient population of the T 1 state due to the high rate of the intersystem crossing process ($ 2 Â 10 12 s À1 ) [4]. Then the T 1 state decays to yield back the ground state in about 800 ns (depending on thioketone concentration).…”

Section: Discussionmentioning

confidence: 99%

“…S 3 absorption bands, thermally activated S 1 -fluorescence, and efficient fluorescence from the S 2 state and phosphorescence from the T 1 state in solution at room temperature [1][2][3]. The long S 2 state lifetime of thioketones (s S 2 ¼ 10 À9 -10 À11 s), due to a large DEðS 2 À S 1 Þ energy gap, is responsible for the S 2 -state fluorescence, whereas emission from the S 1 state (radiative rate constant of about 10 5 s À1 ) is insignificant due to an ultrafast intersystem crossing process to the T 1 state (s S 1 % 10 À12 s) [4]. The S 2 state is known to be extremely reactive in solution because of efficient intermolecular quenching by most solvents including acetonitrile, but except perfluorohydrocarbons (PF) in which the S 2 state decay is exclusively intramolecular [1,3,[5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast quenching of the excited S2 state of benzopyranthione by acetonitrile

Burdziński

Maciejewski

Buntinx

et al. 2004

Chemical Physics Letters

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“…Since population decay processes have been studied extensively, [3,[9][10][11] herein we will focus on phase relaxation dynamics. The vibrational dephasing time in the ground state is shorter than 10 picoseconds in many molecules, whereas the electronic dephasing time of medium-size molecules in solution at room temperature is typically as short as a few tens of femtoseconds.…”

Section: Introductionmentioning

confidence: 99%

Electronic and Vibrational Coherence Dynamics in a Cyanine Dye Studied Using a Few‐Cycle Pulsed Laser

Wang

Kobayashi

2010

ChemPhysChem

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We report the relaxation times of electronic and vibrational coherence in the cyanine dye 1,1',3,3,3',3'-hexamethyl-4,4',5,5'-dibenzo-2,2'-indotricarbocyanine, measured using a 7.1 fs pulsed laser. The vibrational phase relaxation times are found to be between 380 and 680 fs in the ground and lowest excited singlet states. The vibrational dephasing times of the 294, 446, and 736 cm(-1) modes are relatively long among the six modes associated with excited-state wave packets. The slower relaxations are explained in terms of a coupled triplet of vibrational modes, which preserves coherence by forming a tightly bound group to satisfy the condition of circa conservation of vibrational energy. Using data from the negative-time range (i.e., when the probe pulse precedes the pump pulse), the electronic phase relaxation time is found to be 31+/-1 fs. The dynamic vibrational mode in the excited state (1171 cm(-1)), detected in the positive-time range, is also studied from the negative-time traces under the same experimental conditions.

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Subpicosecond population decay time of the first excited singlet state of thioxanthione in fluid solution

Cited by 17 publications

References 23 publications

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Ultrafast quenching of the excited S2 state of benzopyranthione by acetonitrile

Electronic and Vibrational Coherence Dynamics in a Cyanine Dye Studied Using a Few‐Cycle Pulsed Laser

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