Hf

178.49 amu

 dimer vibrational frequency = 176.2 cm-1

 dimer force constant = 1.63 mdyne/Å

References

"Optical and Raman Spectroscopy of Mass-Selected
  Hafnium Dimers in Argon Matrices"

  Z. Hu, Jian-Guo Dong, John R. Lombardi, and D.M. Lindsay,
  J.Phys. Chem., 97, 9263 (1993).

Abstract

The absorption and Raman spectra of hafnium dimers in an argon matrix have been measured. Four weak dimer absorption bands were found between 300 and 700 nm. Resonance Raman spectra (obtained by exciting into a band centered at 620 nm) give we" = 176.2 (26) cm-1with wexe < 1 cm-1. Our results represent the first experimental or theoretical study of the dihafnium molecule.

" Absorption, resonance Raman and Raman excitation
   spectra of hafnium trimers "

Huaiming Wang, Zhendong Hu, Hanae Haouari, Robert Craig, Yifei Liu,
John R. Lombardi, and D. M. Lindsay

Department of Chemistry and Center for Analysis of Structures and interfaces (CASI),
The City College of New York (CCNY), New York, New York 10031

(Received 31 January 1997; accepted 18 February 1997)

J. Chem. Phys. 106 (20),  8339-8343,  22 May 1997

Abstract

We report on the optical, resonance Raman and excitation profile spectra of mass selected hafnium trimers in argon matrices at 14K. The absorption spectrum consists of four overlapping transitions in the range 605 - 620 nm. The Raman spectrum is too complex to be attributed to a single ground state. We may explain the observed spectrum by assumption of five low lying excited states A, B, C, D and E at 319.0 cm-1, 413.4 cm-1, 609.6 cm-1, 642.8 cm-1(weak) and 785.4 cm-1respectively. The ground (X) state, shows complex structure which may be interpreted as the result of a strong, but linear Jahn-Teller effect. Evidence is obtained of pseudo-rotational progressions having states of vibronic angular momentum of  j = ±1/2, ... , ±7/2 based upon a1'  normal frequencies of 142.8 cm-1 and 278.1 cm-1. This indicates a fluxional ground state with E' symmetry in the D3h limit. No such effects are apparent in the low lying excited states, although a1' modes of 143-152 cm-1 are observed and in some cases geometrical information may be inferred. The A state (319.0 cm-1) is geometrically an equilateral triangle (D3h symmetry). The B state (413.4 cm-1) shows and a1' vibration, but without an observed nontotally symmetric mode no geometrical information can be inferred. The C state (609.6 cm-1) shows only a nontotally symmetric mode at 116.7 cm-1, while the D state (642.8 cm-1) and the E state (785.4 cm-1 ) both appear to have D3h symmetry. Raman excitation profiles appear as several distinct types and correlate well with the four absorption bands at  606, 610, 615 and 619 nm.

© 1997 American Institute of Physics. [S0021-9606(97)00620-X]


Table . A summary of the properties of
        the low lying states of Hf3.

State
T0. 
Symmetry
na
ne
X
0 
D3h
(J-T Distorted)
142.8
  
A
319.0 
D3h
152.3
102.7
B
413.4
 ? 
141.7
  
C
609.6
 ?
  
116.7
D
642.8
D3h
149.5
108.4
E
785.4
D3h
150.3
108.7

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