A study of excited state molecular vibrations of aromatic hydrocarbons

Ohno, Koichi

doi:10.1016/0009-2614(79)80244-4

Cited by 23 publications

(5 citation statements)

References 58 publications

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“…The intensity arises from vibronic interaction with the S 2 1 B 2u state. [16][17][18][19] The b-type vibronic band, in contrast, is identified as a transition to an a g vibrational level, the symmetry of which is the same as that of the 0 0 0 band. Although the rotational envelope of a vibronic band observed at 780 cm −1 is strange, this band shape could be reproduced as an envelope of four partially overlapped b-type transitions.…”

Section: ͑1͒mentioning

confidence: 99%

Vibrational and rotational structure and excited-state dynamics of pyrene

Baba

Saitoh

Kowaka

et al. 2009

The Journal of Chemical Physics

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Vibrational level structure in the S(0) (1)A(g) and S(1) (1)B(3u) states of pyrene was investigated through analysis of fluorescence excitation spectra and dispersed fluorescence spectra for single vibronic level excitation in a supersonic jet and through referring to the results of ab initio theoretical calculation. The vibrational energies are very similar in the both states. We found broad spectral feature in the dispersed fluorescence spectrum for single vibronic level excitation with an excess energy of 730 cm(-1). This indicates that intramolecular vibrational redistribution efficiently occurs at small amounts of excess energy in the S(1) (1)B(3u) state of pyrene. We have also observed a rotationally resolved ultrahigh-resolution spectrum of the 0(0) (0) band. Rotational constants have been determined and it has been shown that the pyrene molecule is planar in both the S(0) and S(1) states, and that its geometrical structure does not change significantly upon electronic excitation. Broadening of rotational lines with the magnetic field by the Zeeman splitting of M(J) levels was very small, indicating that intersystem crossing to the triplet state is minimal. The long fluorescence lifetime indicates that internal conversion to the S(0) state is also slow. We conclude that the similarity of pyrene's molecular structure and potential energy curve in its S(0) and S(1) states is the main cause of the slow radiationless transitions.

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Section: ͑1͒mentioning

confidence: 99%

Vibrational and rotational structure and excited-state dynamics of pyrene

Baba

Saitoh

Kowaka

et al. 2009

The Journal of Chemical Physics

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“…It should be also noted that the ground and excited states can differ from each other in bond alternation. For instance, the upshifts of the CC and C−C stretching vibration frequencies in the 2 1 A g state relative to the ground (1 1 A g ) state show the reversal bond alternation in the excited states induced by vibronic coupling between these two states. ,− Various one- and two-photon spectroscopies have revealed that the lowest excited fluorescent state is the 2 1 A g state in polyenes with an intermediate molecular length. ,,,,− …”

Section: Introductionmentioning

confidence: 99%

“…For instance, the upshifts of the CdC and C-C stretching vibration frequencies in the 2 1 A g state relative to the ground (1 1 A g ) state show the reversal bond alternation in the excited states induced by vibronic coupling between these two states. 6, [16][17][18][19][20][21] Various one-and two-photon spectroscopies have revealed that the lowest excited fluorescent state is the 2 1 A g state in polyenes with an intermediate molecular length. 4,5,8,18,[22][23][24][25][26][27][28][29] On the other hand, polyyne possesses a linear carbon framework with a higher degree of bond alternation in the ground (S 0 ) state.…”

Section: Introductionmentioning

confidence: 99%

Symmetry Switching of the Fluorescent Excited State in α,ω-Diphenylpolyynes

et al. 2003

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By using MO calculations based on DFT, absorption, and fluorescence spectroscopy, we have comprehensively studied the low-lying excited singlet states of alpha,omega-diphenylpolyynes (DPY) having 1-6 triple bonds. The a(g) vibrational modes of the C(triple bond)C stretching and of the phenyl ring motion were observed in the fluorescence spectra of diphenylacetylene and 1,4-diphenylbutadiyne. On the other hand, in the fluorescence spectra of the long DPY with the triple-bond number (N) more than two, the phenyl ring motion with a(g) symmetry disappeared and the b(1g) modes of the phenyl ring twisting (approximately 400 cm(-1)) and of the C-H bending (approximately 900 cm(-1)) were detected. The observed fluorescent states of DPY with N < or = 2 and N > or = 3 are assigned to the 1(1)B(1u) (pi(x)pi(x*)) and 1(1)A(u) (pi(x)pi(y*) and/or pi(y)pi(x*)) states, respectively, based on the vibronic structures, the relatively short lifetimes, and the solvatochromic shifts of the fluorescence spectra. Not only the allowed transition of 1(1)B(1u) <-- S(0) but also the forbidden transition of 1(1)A(u) <-- S(0) was detected in the fluorescence excitation spectra of the long DPY with N > or = 3. The low-lying excited state with A(u) symmetry is characteristic in polyyne, which does not exist in polyene. The oscillator strength (f) of the first absorption band in DPY decreases with an increase in N, which is the opposite behavior of the all-trans-alpha,omega-diphenylpolyenes. The N-dependence of the f value is understood by the configuration interaction between the 1(1)B(1u) and 2(1)B(1u) (pi(y)pi(y*)) states, which is consistent with the reduction of the nonlinear optical response of polyyne.

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“…The large stiffening of ν 9 and the mode selectivity as the excitation wavelength is moved closer to the peak of the isolated molecule absorption were predicted by Haas and Zilberg . This shift is found to be ∼100 cm –1 (ν 9 to 1407 cm 1 ), and it is considerably smaller than the ν 9 vibration shift to ∼1566 cm –1 seen in two-photon spectroscopy − and MO calculations . This could be due to imperfect match of the laser wavelength or the large bandwidth of the laser source with respect to the isolated molecule absorption peak in benzene.…”

Section: Resultsmentioning

confidence: 65%

“…9 This shift is found to be ∼100 cm −1 (ν 9 to 1407 cm 1 ), and it is considerably smaller than the ν 9 vibration shift to ∼1566 cm −1 seen in two-photon spectroscopy 15−19 and MO calculations. 20 This could be due to imperfect match of the laser wavelength or the large bandwidth of the laser source with respect to the isolated molecule absorption peak in benzene. Additionally, these data show the strong vibronic coupling of the b 2u modes between the 1 A 1g ground state and the 1…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Resonance-Enhanced Raman Scattering of Ring-Involved Vibrational Modes in the ¹B_2u Absorption Band of Benzene, Including the Kekule Vibrational Modes ν₉ and ν₁₀

et al. 2016

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Resonance Raman spectroscopy provides much stronger Raman signal levels than its off-resonant counterpart and adds selectivity by excitation tuning. Raman preresonance of benzene has been well studied. On-resonance studies, especially at phonon-allowed absorptions, have received less attention. In this case, we observe resonance of many of the vibration modes associated motion of the carbons in the ring while tuning over the (1)B2u absorption, including the related ν9 (CC stretch Herzberg notation, ν14 Wilson notation) and ν10 (CH-parallel bend Herzberg notation, ν15 Wilson notation) vibrational modes along with the ν2 (CC-stretch or ring-breathing Herzberg notation, ν1 Wilson notation) mode and multiples of the ν18 (CCC-parallel bend Herzberg notation, ν6 Wilson notation) vibrational mode. The ring-breathing mode is found to mix with the b2u modes creating higher frequency composites. Through the use of an optical parametric oscillator (OPO) to tune through the (1)B2u absorption band of liquid benzene, a stiffening (increase in energy) of the vibrational modes is observed as the excitation wavelength nears the (1)B2u absorption peak of the isolated molecule (vapor) phase. The strongest resonance amplitude observed is in the 2 × ν18 (e2g) mode, with nearly twice the intensity of the ring-breathing mode, ν2. Several overtones and combination modes, especially with ν2 (a1g), are also observed to resonate. Raman resonances on phonon-allowed excitations are narrow and permit the measurement of vibrations not Raman-active in the ground state.

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A study of excited state molecular vibrations of aromatic hydrocarbons

Cited by 23 publications

References 58 publications

Vibrational and rotational structure and excited-state dynamics of pyrene

Vibrational and rotational structure and excited-state dynamics of pyrene

Symmetry Switching of the Fluorescent Excited State in α,ω-Diphenylpolyynes

Resonance-Enhanced Raman Scattering of Ring-Involved Vibrational Modes in the ¹B_2u Absorption Band of Benzene, Including the Kekule Vibrational Modes ν₉ and ν₁₀

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A study of excited state molecular vibrations of aromatic hydrocarbons

Cited by 23 publications

References 58 publications

Vibrational and rotational structure and excited-state dynamics of pyrene

Vibrational and rotational structure and excited-state dynamics of pyrene

Symmetry Switching of the Fluorescent Excited State in α,ω-Diphenylpolyynes

Resonance-Enhanced Raman Scattering of Ring-Involved Vibrational Modes in the 1B2u Absorption Band of Benzene, Including the Kekule Vibrational Modes ν9 and ν10

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Resonance-Enhanced Raman Scattering of Ring-Involved Vibrational Modes in the ¹B_2u Absorption Band of Benzene, Including the Kekule Vibrational Modes ν₉ and ν₁₀