SCIENTIFIC HIGHLIGHTS 2000-2001
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In the following, the network partners are referred to by the abbreviations given in Table 1.
Table 1: Abbreviations
Bergische Universität-Gesamthochschule Wuppertal
Université Joseph Fourier – Grenoble 1
University of Helsinki
Université Libre de Bruxelles
Centre Regional de la Recherche Scientifique
Délégation Regionale Nord – Pas de Calais –Picardie (DR18)
Centre Regional de la Recherche Scientifique (Orsay)
University College London
Max-Planck-Institut für Kohlenforschung
Ecole Polytechnique Fédérale de Lausanne
On the experimental side of the project, the most important scientific
- The synthesis and first detection of the molecule BF2OH in the
gas phase by infrared spectroscopy. The doublet structure of the
bands shows the existence of a large amplitude bending motion of
the OH group. Recently, the high resolution infrared spectra of
11BF2OH have been recorded at BUGHW.
Some bands have been analyzed by PPM and BUGHW. Furthermore the
microwave and millimeter-wave study of F2BOH has
been started by BUGHW
in collaboration with Dr. J. Demaison at the University of Lille,
France, using the experimental equipment available in Lille (BUGHW,
- Studies of the ground and v4
= 1 excited states of
H2SiF2 have been completed by
BUGHW in collaboration Dr. J. Demaison,
Lille, who contributed millimeterwave measurements and ab initio data
allowing a better assessment of the experimental results.
Spectra of 13CH335Cl and 13CH337Cl
have been recorded, the analysis is
in progress (BUGHW).
- Overtone and combination bands of TeH2 in
the 4500 - 7000 cm-1 region have been recorded at BUGHW, and their
analysis is ongoing jointly with PPM.
- The construction of a
cavity ring-down spectroscopic experiment using a CW titanium-sapphire
ring laser (UNIHEL).
- The analysis of jet-cooled
absorption bands of 12C2H4
was made (PPM in collaboration
- The first high-resolution analysis of the six
fundamental bands of COFCl at high resolution (PPM in collaboration
- Extensive analyses of the
bands of formic acid CHOOH and the detection of the second harmonic
transition near 10200 cm-1 by ICLAS. The rotational analysis of this
transition has been completed at ULB and included in a paper describing
the vibrational energy pattern of formic acid (PPM in collaboration
with UNIJFG and ULB).
- The development of an experimental
set-up called FT-ICLAS for Fourier transform-intracavity laser
absorption spectroscopy. It uses a new Fourier transform spectrometer
installed at ULB at Easter 2001, to record the near-infrared broadband
absorption achieved with the cavity of a sapphire-titanium solid state
laser. Intracavity laser absorption allows very long pathlengths to be
reached, while FTS recording provides significant advantages compared
to conventional spectrographs. At present, the experiment uses a
commercial laser cavity, which had to be significantly modified.
Electronic equipment was developed to synchronise the FTS data handling
and laser pulses. The FT-ICLAS set-up has been used to record spectra
of acetylene with resolution and sensitivity previously unachievable.
Improvements are being brought up regularly on the now existing system.
Simultaneously, the building of a new, more adequate laser cavity has
been started. It has required extensive planning including, in
particular, the writing of a computer program to deal with a "virtual"
cavity in order to allow for selection of optics (ULB in collaboration
- A series of metrological experiments have been
carried out at ULB with the aim of providing reference spectral line
positions in the near-infrared range. These lines will be compiled in a
spectral atlas made available to the scientific community. Spectra of
acetylene and nitrous oxide were recorded and handled, so far. Results
from this work are decribed in a review article with authors from ULB
and UNIJFG, entitled "Vibrational spectroscopic database on acetylene,
This paper has been submitted to J.
Phys. Chem. Ref. Data. It includes in particular an exhaustive
listing of the observed vibrational energy states and complete sets of
predicted vibrational energies and predicted principal rotational
constants Bv up to 15000, 10000 and 12000 cm-1 for
respectively. The measurements are of direct relevance to other
groups in the collaboration, UNIJFG and CNRSDR18.PhLAM, to calibrate
their own laser data. The development of highly sensitive near-infrared
spectrometers by UNIJFG and ULB motivated a collaboration with
CNRSDR18.PhLAM on acetylene. At CNRSDR18.PhLAM, the photo-acoustic
technique has been validated for the fine analysis of spectral line
shapes of this molecule. If validated for the determination of absolute
line intensities, it will become an ideal complement to FT
- Absorption spectroscopy of acetylene
in the 10000-12500 cm-1 spectral region. The
spectra were recorded by Intracavity Absorption Spectroscopy (ICLAS)
using a Ti : Sapphire laser as amplification medium. The rovibrational
analyses of the data were performed in the frame of effective
Hamiltonians. In particular, an anharmonic resonance involving the
stretching and bending modes of
is confirmed. An alternative
approach based on a local mode Hamiltonian was also successfully
applied to the stretching modes of
(UNIJFG in collaboration with
ULB and UNIHEL).
- The vibrational energy pattern in propyne
(methyl acetylene). On the basis of a Fourier Transform spectrum
recorded at ULB and helped by ab initio calculations, an effective
Hamiltonian was developed and a polyad structure of the vibrational
states was put in evidence (UNIJFG in collaboration with ULB).
overtone transitions of deuterated silanes
and SiHD3) were recorded by ICLAS at UNIJFG.
The samples were provided
by BUGHW and a predoc supported by the network has performed the
analysis. The evolution of the rotational structure of the
overtone transitions of monodeuterated silane,
discussed from complementary spectra recorded by Fourier Transform
Spectroscopy at BUGHW
3 and 4) and ICLAS at UNIJFG
6). The analysis of these data has been completed and a paper is in
preparation. Finally, the rotational analysis of the newly observed
VSiH=5 transition of SiH3D
has shown that the upper states of the
transition are mostly unperturbed with characteristic features of local
mode (UNIJFG in collaboration with BUGHW). For
stretching energy structure has been deeply analyzed, combining high
accuracy experiments, ab initio methods, and the relations deduced from
local mode concept. The unprecedented successful inclusion of
electronic structure calculations in the fit of local mode overtone
levels opens a wide field for forthcoming studies on related and other
molecules. So far, these studies have been extended to the spectra of
the asymmetric top
and the symmetric top
collaboration with BUGHW, UNIJFG, UNIHEL and MPKOHLE).
important experimental development was achieved by successfully using
VECSELs (Vertical External Cavity Systems Emitting Lasers) for ICLAS.
This new system opens the near infrared region (below 1
m) to ICLAS.
High quality spectra of acetylene,
already been recorded between 9500 and 10000 cm-1 and are under
- The dipole moment of vibrationally excited
formaldehyde (H2CO) has been measured with a technique that has
previously been proved to work for HOCl (EPFL).
quantum beats have been used as a different approach to dipole moment
measurements at EPFL. This new technique has been used to measure the
dipole moment in the
overtone of formaldehyde, and in highly
vibrationally excited water. The water measurements include the local
mode vibrational states |40-0>, |50-0>,
|80+0> and |40-2>. The
measurements also yield the transition dipole moment between these
states and their counterparts of opposite symmetry, i.e. the transition
dipole moment between
|40-0> and |40+0>. Comparison with calculations
carried out at UCL will give valuable insight into the dipole moment
surface away from the equilibrium position. It is difficult to compute
this part of the dipole moment surface with high accuracy, but it is
important for calculating high overtone intensities.
combination of high accuracy experiments and ab initio methods is
currently applied to analyse the spectrum of FCO2
(a molecule of
atmospheric interest) in various spectral regions (sub-MMW, IR), and
then to determine its structure. (CNRSDR18.PhLAM in collaboration with
BUGHW and MPKOHLE).
- A laser-induced dispersed
vibration-rotation fluorescence experiment has been optimized at
UNIHEL. In acetylene spectra, an improvement of a factor of 7 has been
attained in the signal- to-noise ratio. This experimental technique can
be used to study ortho-para spin conversion in water, a phenomenon
treated theoretically at UCL.
- The laser-induced dispersed
vibration-rotation fluorescence experiment at UNIHEL has been used to
study the first CH stretching overtone FTIR spectrum of diacetylene.
This is a very dense spectrum. Relative to previous work, more precise
wavenumber values were obtained, and more lines could be assigned. The
analysis was carried out in a collaboration between UNIHEL and BUGHW.
The theoretical research has produced the following results:
- Considerable progress has been made in the development of a
Hamiltonian and computer program describing the rotation and vibration
of XY3 molecules using a MORBID-type approach. In parallel, the
calculation of the potential energy surface for ammonia
NH3 is in
progress. A two-dimensional surface (symmetric stretch and symmetric
bend, 440 data points) has been obtained at the CCSD(T) level, with
extrapolation to the basis set limit and inclusion of core correlation
and relativistic corrections. A full six-dimensional surface (14400
data points) has been generated at the CCSD(T)/aug-cc-pVTZ level.
- Intensities of overtone and combination
bands of SiH4 and SiHCl3 have been
investigated by ab initio methods,
in particular by means of many-dimensional CCSD(T) dipole moment
surfaces. This work has now been extended to GeH4. The results
rationalize the experimental findings (including intensity anomalies)
and highlight the reliability of high-level ab initio predictions
- New assignments of H2O and HDO spectra have been
made, both for hot molecules in the mid infrared and for cold molecules
in the near infrared/optical. New ab initio studies show the importance
of various electronic relativistic effects, including qed corrections,
on the potential for water. A new database containing all known
experimental energy levels for water (over 12,000) has been
constructed. Further, all quasi-degenerate ortho-para states in H2O
have been analysed; this analysis produced a list of candidate states,
which could be suitable for experimental observation, possibly using
the experimental techniques at UNIHEL (UCL).
- A new ab initio
potential energy surface for H2S including electronic relativistic and
adiabatic corrections has been developed. Nuclear motion calculations
using this surface show much greater accuracy than previous studies
- A new, global ab initio potential energy and dipole
moment surfaces for the isomerizing HCN/HNC system have been calculated
and used for rotation-vibration calculations extending above the
barrier between the isomers. Detailed spectroscopic studies and
comparison with experiment have been made (UCL).