Three types of analyses: generalized conventional spectroscopic analysis, statistical analysis, and hierarchical
analysis, by which we aim to extract dynamical information from the complex spectrum of small
polyatomic molecules are reviewed by referring to recent studies on vibrationally highly excited acetylene.
A convolution analysis, one type of hierarchical analysis, is performed on the dispersed fluorescence
spectrum of acetylene to demonstrate its practical applicability. Based on previous studies, as well as
on the convolution analysis, a systematic and efficient procedure to treat such complex spectra is
discussed.

Kaoru  Yamanouchi

Jun  Miyawaki

Soji  Tsuchiya

David M. Jonas

Robert W. Field

New Scheme for Extracting Molecular Dynamics from Spectra: Case Study on Vibrationally Highly Excited Acetylene

The &#195;1Au &#8592; <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mtext>X</mml:mtext><mml:mo>&#x02DC;</mml:mo></mml:mover></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi></mml:mi><mml:mn>1</mml:mn></mml:msup><mml:msubsup><mml:mo>&#x2211;</mml:mo><mml:mi>g</mml:mi><mml:mo>+</mml:mo></mml:msubsup></mml:math>
 electronic transition of the vibrationally excited acetylene molecule was studied by
IR&#8211;UV double resonance spectroscopy in gas and in a supersonic jet. The C&#8211;H antisymmetric stretching
vibration <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BD;</mml:mi><mml:mrow><mml:mtext>CH</mml:mtext></mml:mrow></mml:msub></mml:math>ant in the &#195; state was clearly observed when the molecule was excited to the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BD;</mml:mi><mml:mrow><mml:mtext>CH</mml:mtext></mml:mrow></mml:msub></mml:math>sym &#43; <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BD;</mml:mi><mml:mrow><mml:mtext>CH</mml:mtext></mml:mrow></mml:msub></mml:math>ant
combination vibration in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mtext>X</mml:mtext><mml:mo>&#x02DC;</mml:mo></mml:mover></mml:math> state by the IR laser. When the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BD;</mml:mi><mml:mrow><mml:mtext>CH</mml:mtext></mml:mrow></mml:msub></mml:math>ant fundamental vibration was excited,
the C&#8211;H in-plane cis-bending vibration &#957;cis(in) in the &#195; state was observed strongly, while <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BD;</mml:mi><mml:mrow><mml:mtext>CH</mml:mtext></mml:mrow></mml:msub></mml:math>ant almost
disappeared. The difference was interpreted in terms of Fermi resonance of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BD;</mml:mi><mml:mrow><mml:mtext>CH</mml:mtext></mml:mrow></mml:msub></mml:math>ant fundamental vibration
in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mtext>X</mml:mtext><mml:mo>&#x02DC;</mml:mo></mml:mover></mml:math>. The predissociation threshold was newly determined to be 46,439&#764;46,673 cm&#45;1 (133.11 &#177; 0.33 kcal/mol). In the region above the predissociation threshold, strong vibrational mixing was found. The
higher members of the progression of the trans-bending vibration starting from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>&#x03BD;</mml:mi><mml:mrow><mml:mtext>CH</mml:mtext></mml:mrow></mml:msub></mml:math>ant were assigned. It
was suggested that the nonradiative relaxation accelerated in the region above 51,744 cm&#45;1.

Masaaki  Fujii

Shigeki  Tanabe

Yasuo  Okuzawa

Mitsuo  Ito

IR-UV Double Resonance Spectrum of Acetylene Below and Above the Predissociation Threshold

Absorption spectra are detected for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>C</mml:mtext><mml:mrow><mml:mn>60</mml:mn></mml:mrow><mml:mo>&#x2212;</mml:mo></mml:msubsup></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>C</mml:mtext><mml:mrow><mml:mn>60</mml:mn></mml:mrow><mml:mo>2&#x2212;</mml:mo></mml:msubsup></mml:math> produced electrolytically in solution at room temperature.
Theoretical analysis of the spectrum of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>C</mml:mtext><mml:mrow><mml:mn>60</mml:mn></mml:mrow><mml:mo>&#x2212;</mml:mo></mml:msubsup></mml:math> by CNDO/S calculations gives an interpretation of the characteristic
near-IR bands, the weak visible bands, and the strong bands in the UV region. The emission
spectrum of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>C</mml:mtext><mml:mrow><mml:mn>60</mml:mn></mml:mrow><mml:mo>&#x2212;</mml:mo></mml:msubsup></mml:math> is a mirror image of the near-IR absorption band, and the detection of the emission
reconfirms our original assignment of the absorption spectrum. The nature of the spectrum of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>C</mml:mtext><mml:mrow><mml:mn>60</mml:mn></mml:mrow><mml:mo>2&#x2212;</mml:mo></mml:msubsup></mml:math> is
characterized by a similar orbital picture to that of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>C</mml:mtext><mml:mrow><mml:mn>60</mml:mn></mml:mrow><mml:mo>&#x2212;</mml:mo></mml:msubsup></mml:math>. Further laser experiments of significance are
proposed.

Tatsuhisa  Kato

Absorption and Emission Spectra for C60 Anions

The fluorescence/phosphorescence excitation spectra, the dispersed fluorescence/phosphorescence spectra
and the sensitized phosphorescence excitation spectrum have been measured for jet-cooled p-benzoquinone.
The assignments of vibronic bands in the 1B1g(n&#45;,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>&#x03C0;</mml:mi><mml:mo>&#x2217;</mml:mo></mml:msup></mml:math>) &#8592; 1Ag and 1Au(n&#43;,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>&#x03C0;</mml:mi><mml:mo>&#x2217;</mml:mo></mml:msup></mml:math>) &#8592; 1Ag transitions
have been definitely established. The phosphorescence spectra from vibronic levels of 3Au exhibit a
feature of single vibronic level emission. The 3Au &#8592; 1Ag transition was also vibrationally analyzed.

Isamu  Suzuka

Masaomi  Sanekata

Nobuhiro  Ohta

Singlet And Triplet n,<svg style="vertical-align:-0.1638pt" height="13.95" version="1.1" viewBox="0 0 17.775 13.95" width="17.775" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,13.688)"><path id="x1D70B" d="M574 449q-23 -58 -38 -79q-16 -4 -79 -4q-27 -100 -46 -219q-14 -87 7 -87t74 36l13 -27q-74 -81 -139 -81q-48 0 -48 62q0 22 8 59l60 258l-154 4q-21 -103 -54.5 -209t-64.5 -151q-38 -23 -83 -23l-7 15q46 36 94 152.5t64 216.5q-81 0 -138 -54l-18 23q22 27 39.5 43&#xA;t61.5 33.5t100 17.5q43 0 131.5 -2.5t129.5 -2.5q23 0 33.5 5t24.5 25z" /></g><g transform="matrix(.012,-0,0,-.012,10.113,5.525)"><path id="x2217" d="M471 153q-22 -15 -61 -13q-25 31 -45.5 49.5t-56.5 41.5q4 -71 28 -134q-17 -33 -42 -46q-24 12 -42 46q24 63 28 134q-36 -23 -56.5 -41.5t-45.5 -49.5q-36 -2 -61 13q0 28 19 59q65 10 130 43q-65 33 -130 43q-19 31 -19 59q22 15 61 13q25 -31 45.5 -49.5t56.5 -41.5&#xA;q-4 71 -28 134q17 33 42 46q24 -12 42 -46q-24 -63 -28 -134q36 23 56.5 41.5t45.5 49.5q36 2 61 -13q0 -28 -19 -59q-65 -10 -130 -43q65 -33 130 -43q19 -31 19 -59z" /></g></svg> Transitions of Jet-Cooled p-Benzoquinone

High resolution photoelectron spectra are reported for styrene and stilbene with an emphasis on identifying
the low frequency modes which are important in the phenyl&#8211;vinyl torsional motion. In the styrene
cation three low frequency out-of-plane vibrations are measured, &#957;42, &#957;41 and &#957;40 as well as a number
of higher frequency in plane modes. Generally the low frequency modes do not appear with significant
intensity but by pumping the appropriate modes in the S1 intermediate state the intensity for these modes
in the threshold ionization spectrum is quite good. In the stilbene cation the analogous phenyl&#8211;vinyl
torsion, &#957;37, is also measured as well as the related mode &#957;36. The ethylene torsional mode in stilbene
is not observed. In both molecules the observed frequencies are used to relate the electronic structure
of the cation to the S1 and S0 states of the molecule.

Jonathan M. Smith

J. L. Knee

Threshold Ionization Spectroscopy of the Low Frequency Vibrational Modes of Styrene and Trans-Stilbene Cations

Mitsuo Ito

Foreword

Investigations of the collisional interactions between sodium atoms in the 32P states and helium and hydrogen gases are described. Studies of collision-induced mixing and quenching interactions have been carried out under conditions where chemical reaction to produce sodium hydride is possible. Thus the sodium number derivatives are sufficient for radiation trapping to occur. This is in contrast to virtually all previous investigations in which conditions were such that this effect need not be considered. The intensity and temporal behaviour of laser induced fluorescence (LIF) resulting from the photoexcitation of the sodium 32P states is monitored as a function of foreign gas pressure. Whilst many of the features observed are to be expected, results show how radiation trapping strongly influences cross-section determination. The need for a more rigorous treatment of collision cross-sections under these conditions, which are often more realistic than the &#8216;ideal&#8217; trapping free situations, is demonstrated.

L. H. Vassie

H. H. Telle

Radiative Lifetimes and Collision Processes in Sodium-Rare Gas and Sodium-Hydrogen Systems

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Laser Chemistry