High resolution laser spectroscopy of asymmetrically deuterated cyclopentadienyl radicals: A study of vibronic degeneracy resolution and Jahn–Teller distortion

Yu, Lian; Cullin, David W.; Williamson, James M.; Miller, Terry A.
February 1993
Journal of Chemical Physics;2/15/1993, Vol. 98 Issue 4, p2682
Academic Journal
The rotationally resolved, laser induced fluorescence, excitation spectra of the partially deuterated cyclopentadienyl radicals, C5H4D and C5HD4, have been observed at low temperature in a supersonic free jet expansion. The observed electronic transition in the uv region corresponds to the A 2A‘2[larger_closed_square]X 2E‘1 transition in the symmetric cyclopentadienyl isotopomers with D5h symmetry. In the reduced C2v symmetry of the C5HD4 and C5H4D isotopomers, this electronic transition splits into two distinct vibronic bands, separated by about 9 cm-1, which arise from the two vibronic components X1 and X2 into which the X state is resolved when the symmetry is lowered. In C5H4D the ground X1 state has 2A2 symmetry and a permanently distorted, elongated allyl-like structure while the low-lying X2 state has 2B2 symmetry and a compressed dienelike structure. The symmetries of the energy levels and the distortions are reversed for the C5HD4 species. A detailed theoretical model is developed to describe the splitting and the rotational structure of the X1 and X2 states. Application of this model yields a precise value for the alternation of the C–C bond lengths in the distorted structures. This value is shown to be the same as that describing the dynamically pseudorotating, Jahn–Teller distorted structures in the D5h isotopomers. Additionally, the theory explains anomalous values of the observed inertial defects and relates them to physically meaningful quantities for all the isotopomers in both their X1 and X2 states. Our results are compared to previous experimental work and ab initio calculations on the cyclopentadienyl radical.


Related Articles

  • Relativistic many-body calculations of excitation energies, line strengths, transition rates, and oscillator strengths in Pd-like ions. Safronova, U. I.; Cowan, T. E.; Johnson, W. R. // Canadian Journal of Physics;Aug2005, Vol. 83 Issue 8, p813 

    Excitation energies, line strengths, oscillator strengths, and transition probabilities are calculated for 4d�14f, 4d�15p, 4d�15f, and 4d�16p hole�particle states in Pd-like ions with nuclear charges Z ranging from 49 to 100. Relativistic many-body perturbation theory...

  • Electron excitation of the Group IV elements. Srivastava, R.; P. McEachran, R.; D. Stauffer, A. // Canadian Journal of Physics;Jun2002, Vol. 80 Issue 6, p687 

    We investigated the electron excitation of the fine-structure levels of the [SUP3]P ground state and the first excited [SUP]D state of the first four elements of Group IV: carbon, silicon, germanium, and tin. These calculations were carried out in the j-j coupling scheme using the relativistic...

  • Condensed excited states in calcium. Popov, A. V. // Plasma Physics Reports;Apr2006, Vol. 32 Issue 4, p332 

    A method of calculating the spectral characteristics of excited atoms with allowance for the widths of the energy levels is proposed. It is shown that conditions can be created for the formation of condensed excited states in the optical range of the excitation energies. Long-lived excited...

  • Five-body Cluster Structure of the double Λ hypernucleus 11ΛΛBe. Hiyama, Emiko // EPJ Web of Conferences;2012, Issue 20, p1 

    Energy levels of the double Λ hypernucleus, 11ΛΛ Be are calculated within the framework of an ααnΛΛ five-body model. By comparing our results and recent observed data at KEK-E373 experiment, the Hida event, we suceeded in interpreting as an observation of the ground...

  • One- and two-photon excitation vibronic spectra of 2-methylallyl radical at 4.6–5.6 eV. Chen, Chun-Cing; Wu, Hsing-Chen; Tseng, Chien-Ming; Yang, Yi-Han; Chen, Yit-Tsong // Journal of Chemical Physics;7/1/2003, Vol. 119 Issue 1, p241 

    Vibronically excited 2-methylallyl radical [CH[SUB2]C(CH[SUB3])CH[SUB2]] at 4.6-5.6 eV has been studied by 1+1 and 2+2 resonance-enhanced multiphoton ionization (REMPI) spectroscopy. The 2-methylallyl radicals were produced by the flash pyrolysis of 3-bromo-2-methylpropene in a supersonic-jet...

  • Energy Spectrum of Two-Particle Cruciform Quantum Wires. Escorcia-Salas, G.; Mikhailov, I.; Sierra-Ortega, J. // Journal of Superconductivity & Novel Magnetism;Jun2013, Vol. 26 Issue 6, p2223 

    We analyze the energy spectrum of a heterostructure with two particles separated in two crossed wires with parabolic confinement along their axes. We show that the energy spectrum in the limit of extremely strong confinement does not depend on the type of the interaction, and it is similar to...

  • Diode laser spectroscopy of the four radicals, CdD, ZnD, BaD, and SrD, in their 2∑ ground state. Birk, Helmut; Urban, Rolf-Dieter; Polomsky, Petra; Jones, Harold // Journal of Chemical Physics;4/15/1991, Vol. 94 Issue 8, p5435 

    The infrared spectra of several isotopic forms of the monodeuterides of the metals cadmium, zinc, barium, and strontium have been measured in their ground electronic state (2∑) in the gas phase using a diode laser spectrometer. The analysis of the experimental data was carried out in two...

  • Observation of the 2ν2(l=2)←0 overtone band of H+3. Xu, Li-Wei; Gabrys, Charles; Oka, Takeshi // Journal of Chemical Physics;11/1/1990, Vol. 93 Issue 9, p6210 

    The overtone band of 2ν2(l=2)←0 of H+3 in the 2 μm infrared region has been observed in absorption by using a difference frequency laser spectrometer. The LiIO3 nonlinear optical system assembled by Bawendi and the bidirectional multiple path optical arrangement with velocity...

  • Laser spectroscopy of NiBr: Ground and low-lying electronic states. Leung, J. W-H.; Wang, Xianghuai; Cheung, A. S-C. // Journal of Chemical Physics;8/22/2002, Vol. 117 Issue 8, p3694 

    Four electronic states of NiBr have been studied using the technique of laser vaporization/reaction with supersonic cooling and laser induced fluorescence (LIF) spectroscopy. NiBr molecules were produced by reacting laser ablated nickel atoms and ethyl bromide (C[sub 2]H[sub 5]Br). High...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics