J/ApJ/662/1309      Rotational spectra of small PAHs         (Thorwirth+, 2007)
================================================================================
Rotational spectra of small PAHs: acenaphthene, acenaphthylene, azulene,
and fluorene.
    Thorwirth S., Theule P., Gottlieb C.A., McCarthy M.C., Thaddeus P.
   <Astrophys. J., 662, 1309-1314 (2007)>
   =2007ApJ...662.1309T
================================================================================
ADC_Keywords: Atomic physics
Keywords: astrochemistry - ISM: molecules - molecular data

Abstract:
    Pure rotational spectra of four small polycyclic aromatic hydrocarbons
    have been observed by Fourier transform microwave spectroscopy of
    a molecular beam in the frequency range from 7 to 37GHz. Initial
    searches for acenaphthene (C_12_H_10_), acenaphthylene (C_12_H_8_), and
    fluorene (C_13_H_10_) were guided by quantum chemical calculations
    performed at the B3LYP/cc-pVTZ level of theory. All three molecules
    exhibit b-type rotational spectra and are calculated to be moderately
    polar, with dipole moments of 0.3-0.9D. Close agreement (to better
    than 1%) between the calculated equilibrium and experimentally derived
    ground-state rotational constants is achieved. Selected transitions of
    acenaphthene and fluorene have also been measured in the 3mm region
    by conventional free-space absorption spectroscopy, as have
    transitions of the previously studied azulene (C_10_H_8_). The data
    presented here facilitate deep radio astronomical searches with large
    radio telescopes.

File Summary:
--------------------------------------------------------------------------------
 FileName   Lrecl  Records   Explanations
--------------------------------------------------------------------------------
ReadMe         80        .   This file
table1.dat     46      115   Experimental rotational transition frequencies
                              of Azulene (C_10_H_8_)
table3.dat     46      227   Selected experimental rotational transition
                              frequencies of Acenaphthene (C_12_H_10_)
table6.dat     46       57   Selected experimental rotational transition
                              frequencies of Acenaphthylene (C_12_H_8_)
table8.dat     46      114   Selected experimental rotational transition
                              frequencies of Fluorene (C_13_H_10_)
--------------------------------------------------------------------------------

Byte-by-byte Description of file: table*.dat
--------------------------------------------------------------------------------
   Bytes Format Units   Label     Explanations
--------------------------------------------------------------------------------
   1-  3  I3    ---     J'        The upper J quantum number
   5-  6  I2    ---     Ka'       The upper Ka quantum number
   8- 10  I3    ---     Kc'       The upper Kc quantum number
  12- 14  I3    ---     J"        The lower J quantum number
  16- 17  I2    ---     Ka"       The lower Ka quantum number
  19- 21  I3    ---     Kc"       The lower Kc quantum number
  23- 32  F10.4 MHz     Freq      The experimental frequency of the transition
  34- 40  F7.4  MHz     O-C       The observed minus calculated value
  42- 46  F5.3  MHz   e_Freq      Estimated experimental uncertainty in Freq
--------------------------------------------------------------------------------

History:
    From electronic version of the journal
================================================================================
(End)                  Greg Schwarz [AAS], Patricia Vannier [CDS]    22-May-2009