“…The spectrum is in good agreement with the one published by Shida 2b. In accordance with earlier observations, − , we find that increasing the BD concentration leads to an additional band at 425 nm (Figure B), which arises from dimer cations and possible other secondary products that may be formed through interaction with matrix molecules. 1 (A) Electronic absorption spectrum of the radical cation of 1,3-butadiene prepared by γ-irradiation of a 5 × 10 -3 M solution of 1,3-butadiene in the Freon mixture at 77 K. The vertical arrow indicates the excitation wavelength for the resonance Raman spectrum of Figure .…”
Section: Resultssupporting
confidence: 92%
“…Photoelectron spectroscopy can directly reveal the electronic states of the molecular ion, 4,5a primarily those which arise from electron configurations obtained by the removal of one electron from a doubly occupied molecular orbital (MO) of the ground-state neutral. 6,9 Electronic absorption spectra of BD •+ in different rigid media have been reported, 2b, [9][10][11][12][13][14][15][16] and its gas-phase photodissociation spectrum has been published. 7 States arising solely from non-Koopmans configurations, configurations that are described by the simultaneous ejection of one electron and the promotion of another from an occupied to a virtual orbital in the neutral molecule, are usually not observed in the photoelectron spectrum.…”
Section: Introductionmentioning
confidence: 99%
“…Electronic absorption spectra of BD •+ in different rigid media have been reported, 2b,− and its gas-phase photodissociation spectrum has been published. , Despite the earlier discrepancies between the spectra published by different groups, it is now well established that BD •+ itself shows two absorption bands at 295 and 550 nm, whereas the other bands observed at higher concentrations at 425 and 1200 nm arise from dimer cations and secondary products that are probably formed through interaction with matrix molecules.…”
We report the resonance Raman spectrum of the 1,3-butadiene radical cation generated by γ-irradiation in a Freon glass. The spectrum is excited at 550 nm in resonance with the first absorption band. The spectrum, which is interpreted with the help of density functional theory calculations and a recently published scaled quantum mechanical force field, indicates the presence of both the s-trans and the s-cis rotamers of the butadiene radical cation.
“…The spectrum is in good agreement with the one published by Shida 2b. In accordance with earlier observations, − , we find that increasing the BD concentration leads to an additional band at 425 nm (Figure B), which arises from dimer cations and possible other secondary products that may be formed through interaction with matrix molecules. 1 (A) Electronic absorption spectrum of the radical cation of 1,3-butadiene prepared by γ-irradiation of a 5 × 10 -3 M solution of 1,3-butadiene in the Freon mixture at 77 K. The vertical arrow indicates the excitation wavelength for the resonance Raman spectrum of Figure .…”
Section: Resultssupporting
confidence: 92%
“…Photoelectron spectroscopy can directly reveal the electronic states of the molecular ion, 4,5a primarily those which arise from electron configurations obtained by the removal of one electron from a doubly occupied molecular orbital (MO) of the ground-state neutral. 6,9 Electronic absorption spectra of BD •+ in different rigid media have been reported, 2b, [9][10][11][12][13][14][15][16] and its gas-phase photodissociation spectrum has been published. 7 States arising solely from non-Koopmans configurations, configurations that are described by the simultaneous ejection of one electron and the promotion of another from an occupied to a virtual orbital in the neutral molecule, are usually not observed in the photoelectron spectrum.…”
Section: Introductionmentioning
confidence: 99%
“…Electronic absorption spectra of BD •+ in different rigid media have been reported, 2b,− and its gas-phase photodissociation spectrum has been published. , Despite the earlier discrepancies between the spectra published by different groups, it is now well established that BD •+ itself shows two absorption bands at 295 and 550 nm, whereas the other bands observed at higher concentrations at 425 and 1200 nm arise from dimer cations and secondary products that are probably formed through interaction with matrix molecules.…”
We report the resonance Raman spectrum of the 1,3-butadiene radical cation generated by γ-irradiation in a Freon glass. The spectrum is excited at 550 nm in resonance with the first absorption band. The spectrum, which is interpreted with the help of density functional theory calculations and a recently published scaled quantum mechanical force field, indicates the presence of both the s-trans and the s-cis rotamers of the butadiene radical cation.
“…It obviously corresponds to the allowed transition 2B, (n4) +-2A, ( z~)~) , especially if allowance IS made for a slight red-shift of the condensed-phase absorption of 1' with respect to the corresponding gas-phase PE. band of 1 (see also [3]). From the shape of the orbitals involved in the transition (Fig.…”
SummaryThe radical cations of indeno [2,l-a]indene (l), stilbene (2) and 3,5,3', 5'-tetramethylstilbene (3) were prepared by y-irradiation of the neutral precursors in an electron-scavenging matrix at 77 K. Their electronic spectra were recorded and compared to the photoelectron spectra (PE.) of the neutral precursors. The results show that either the fourth or the fifth excited doublet state of the cations is of "on-Koopmans'-type, with specific doublet energy (D) D (2B,) = 2.74 eV (1 +), =2.59 eV (2+), =2.49 eV (3+). Remarkably, 1' possesses two electronic states in the 2.7-2.8 eV energy range: 2A, ('Koopmans'-type) and 2B, ("on-Koopmans'-type). The 'SDT-equation D = approximately connecting excited singlet (S) and triplet (T) states of a neutral alternant system with the excited doublet (D) states of its radical cation -provided e--promotion occurs for all three excited states between the same (paired) orbitals -is satisfyingly exemplified by 1: S l = 3.92 eV and TI = 2.06 eV for 1, D40r5= 2.74 eV for 1 +.Introduction. -We have recently reported [2] an equation (henceforth called 'SDT'-equation') which interconnects the energies of excited singlet (S) and triplet (T) states of an alternant system M to those of the excited doublet (D) states of the corresponding radical cation M', provided a) the electron promotions leading to the above three excited states involve the same two MO's which furthermore are 'paired' ones; b) the frozen orbital approximation holds; c) the ZDO-approximation holds.Neglecting configuration interaction (CI.) then leads to Equation I for the corresponding energies [2]: 1 2
“…Such spectra have traditionally been obtained by matrix isolation (y-ray radiolysis of dilute solutions in a low temperature organic glass matrix [2][3][4]), or chemical preparation [S,6]. In the glassy matrices, the potential chemistry of the i~mobilized ions is restricted to unimolecular processes.…”
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