My recent scientific activity has been devoted to research in
the field of the molecular spectroscopy on the following
subjects
- Rovibrational analysis of the fundamental, overtone and
combination bands of perchloryl fluoride observed in the high
resolution infrared spectra of the pure isotopic samples of
F35Cl16O3, F37Cl6O3, F35Cl18O3 and F37Cl18O3 recorded from 450 to
2200 cm-1. Determination of the molecular constants in the analysed
states and of the anharmonic or vibro-rotational interactions
constants effective between those states.
- Determination of the anhamonicity constants xij of the
perchloryl fluoride from the combination of the band origins and
evaluation of the rotation vibration interaction parameters from
the rotational constants in the vibrational excited states.
Determination of the equilibrium geometry of FClO3 from the
equilibrium rotational constants.
- Calculation of the ab initio anharmonic force field of FClO3
and comparison of the calculated fundamental frequencies, of the
anharmonicity constants and of the vibration rotation interaction
constants with the experimental corresponding ones.
- Calculation of the ab initio anharmonic force field of
naphthalene-h8 and naphthalene-d8 with the DFT method, using the
B97-1 functional and TZ2P basis set. The calculated frequencies of
the fundamental modes of vibration are compared with the
experimental counterparts, to assign the vibration spectra of these
molecules.
- Calculation of the ab initio anharmonic force field of
1,3-cyclepentadienes with the DFT method, using the B97-1
functional and TZ2p basis set. The calculated frequencies of the
fundamental modes of vibration are compared to the experimental
counterparts, to assign the vibration spectra of C5H6, C5D6, C5H5D
and C5HD5.
- Analysis of the 3nu1 band system spectra of cyanoacetylene
recorded at high resolution with the FT and ICLAS VECSEL
techniques. Determination of the molecular constants of the
observed bands in this system and evaluation of the nature of
the lower and upper states of the observed transitions.
- Vibro-rotational analysis of the high resolution infrared bands
of acetylene and its isotopic derivatives recorded from the
far-infrared to the near infrared, to characterise the states
involved in the transitions and to derive the molecular constants
of the various isotopic species in the excited states.
- High resolution infrared study of the first and second
stretching overtone systems of SbD3. The aim is to characterise the
analysed excited states form a spectroscopic point of view, i.e. to
determine the energies of the rotational levels, the band origins
the molecular constants and the interaction parameters of those
excited states. The local mode model is used to describe the
behaviour of the Sb-D stretching highly excited states also in
comparison to the Sb-H ones.
- High resolution infrared study of the ground state, of the nu1
fundamental, and of the first overtone of nu1 of the asymmetric
rotor SbHD2. The aim is to characterize the analysed states and to
test the applicability of the extended local mode theory to the
description of the overtone state.
- The high resolution spectrum of diacetylene from 500 to 1000
cm-1 has been recorded and analysed. The nu8 fundamental, the
n7+n9 combination, the nu3-nu9 difference band and the nu8+nu9-nu9
and nu7 +2nu9-nu9 hot bands have been assigned and rovibrational
analysed. The anharminic resonance effective between the v3 =1 ,
v8=v9=1 and V7=2 states have been considered in the model
Hamiltonian. Very precise spectroscopic parameters of the
excite states have been obtained.
-
The infrared spectrum of the ammonia isotopologue 15ND3 has been
investigated by high resolution Fourier transform spectroscopy in
the region from 450 to 1600 cm-1. In total, 2217 transitions
involving the (s) and (a)
inversion-rotation-vibration levels have been identified and
assigned to the n2 and n4 bending fundamentals. The assigned
transitions have been fitted simultaneously using an
inversion-rotation-vibration effective Hamiltonian which includes
all symmetry allowed interactions between and within the excited
state levels. The adopted model has been successful in
rationalizing the complicated energy level pattern. Accurate values
for the vibration and rotation spectroscopic constants, including
11 interaction coefficients, have been obtained for both inversion
levels of the v2 = 1 and v4 = 1 states. The standard deviation of
the fit, 0.00071 cm-1, is about two times the estimated measurement
precision.
-
The 2nu1 (A1), Si-H stretching overtone band of HSiD3 has been
recorded at a resolution of ca. 0.009 cm-1 between 4200 and 4400
cm-1. About 790 ro-vibration transitions of the H28SiD3
isotopologue have been assigned, with J ' up to 24 and
K up to 21. The spectrum evidences the existence of several
perturbations. The assigned transitions have been analyzed either
neglecting or including in the model A1/E Coriolis-type
interactions between v1 = 2 and nearby dark states. The standard
deviation of all the fits is, however, more than one order of
magnitude larger than the estimated experimental precision and is
independent of the adopted model.
-
The FTIR spectra of CH2ClF (natural isotopic mixture) and
CH237ClF (isotopically enriched sample) were investigated in the n5
and 2n6 region between 700 and 800 cm-1 at a resolution of 0.004
cm-1. The nu5 and 2nu6 vibrations of A' symmetry give rise to
a/b hybrid bands with a very predominant
a-type component. Due to the proximity of their band
origins, the v5 = 1 and v6 = 2 levels perturb each other by Fermi
and Coriolis resonances. The interaction mechanisms, previously
investigated in the rotational spectra of CH235ClF, were extended
to the less abundant isotopic species CH237ClF and to higher
J and Ka values in the main isotopologue. The
spectral analysis resulted in the identification of 4188 and
5392 transitions for CH235ClF and CH237ClF, respectively. All the
assigned data were simultaneously fitted using the Watson's
A-reduction Hamiltonian in the Ir representation and perturbation
operators. Excited state parameters, band origins and coupling
terms for the nu5/2nu6 dyad of both isotopologues were
determined.
14. Diacetylene,
C4H2, has been identified in several astronomical environments
through its infrared spectrum. In contrast, monodeuterated
diacetylene (DC4H) has not been detected in space so far owing to
the low isotopic abundance of deuterated species but also to the
rather poor laboratory spectroscopic characterisation of this
molecule. Aims. The aim of this work is to provide accurate
spectroscopic parameters for DC4H to achieve reliable predictions
for both its spectra at millimetre and infrared wavelengths.
Methods. We studied the rotational spectrum of DC4H in the range
85-615 GHz by millimetre-wave spectroscopy and the infrared
spectrum below 1000 cm(-1) by high-resolution, Fourier-transform
spectroscopy. Several pure rotational transitions were recorded in
the ground state and in excited vibrational bending states. The
three fundamental bands v(6), v(7), and v(8) have been identified
and assigned in the infrared spectrum. Results. The rotational
transitions were analysed together with the infrared data in a
global fit that produces very accurate rovibrational parameters.
The observed frequencies and wavenumbers are reported to provide
precise guidance for astronomical searches.
15.The infrared spectrum of the perdeuterated acetylene, 12C2D2,
has been recorded from 900 cm−1 to 5500 cm−1 by Fourier transform
spectroscopy at a resolution ranging between 0.004 and 0.009 cm−1.
Ninety-two bands involving the ν1, ν2, and ν3 stretching modes,
also associated with the ν4 and ν5 bending vibrations and 9 bands
involving pure bending transitions have been observed and analysed.
In total, 8345 transitions for the stretching-bending, and 862 for
the pure bending modes have been assigned in the investigated
spectral region. All the transitions relative to each stretching
mode, i.e. the fundamental, its first overtone, and associated hot
and combination bands involving bending states up to v 4 +
v 5 = 2, were fitted simultaneously. The Hamiltonian adopted
for the analysis is that appropriate to a linear molecule and
includes vibration and rotation l-type interactions. The
Darling−Dennison interaction between v 4 = 2 and v 5
= 2 levels associated with the various stretching states was also
considered. The standard deviation for each global fit is smaller
than 0.0006 cm−1, of the same order of magnitude of the measurement
precision.
16. The high-resolution infrared spectrum of monodeuterated
diacetylene has been recorded in the 4501100 cm(-1) spectral region
by Fourier transform infrared spectroscopy. Seven new bands have
been identified: the nu(3) fundamental (C-C stretch), and the nu(8)
+ nu(9), nu(7) + nu(8), 2 nu(7), 2 nu(8), nu(8) + nu(9) - nu(9),
and nu(6) + nu(9) - nu(9) combination, overtone, and hot bands. The
assigned transitions, together with those previously reported for
the fundamental bands [F. Tamassia, L. Bizzocchi, C. Degli Esposti,
L. Dore, M. Di Lauro, L. Fusina, M. Villa, and E. Cane, Astron.
Astrophys. 549, A38 (2013)], form a comprehensive data set which
comprises more than 2500 ro-vibrational transitions, and involves
all singly and most doubly excited vibrational states of DC4H lying
below 1000 cm(-1). Rotational and vibrational l-type resonance
effects among the sub-levels of excited bending states were
considered in the analysis, which also included a careful treatment
of the various anharmonic interactions coupling many vibrational
states lying above 600 cm(-1). Reliable and unambiguous
spectroscopic parameters were obtained for each investigated state,
including the rotational and centrifugal distortion constants B-nu
and D-nu, the l-type doubling parameter q(t), the anharmonicity
constants x(L)(89), x(L)(69), and the vibrational l-type terms
r(89), r(69) for the upsilon(8) = upsilon(9) = 1 and upsilon(6) =
upsilon(9) = 1 bend-bend combination states. (C) 2013 AIP
Publishing LLC.
17. Infrared spectra of deuterated monofluoroacetylene, DCCF,
have been recorded in the region between 320 and 850 cm-1 at an
effective resolution ranging from 0.0024 to 0.0031 cm-1. In total,
6650 rotation vibration transitions were assigned to 37 bands
involving the bending states with v4 + v5 and
|l4 + l5|, respectively, up to 3, allowing the
characterization of the ground state and of 18 vibrationally
excited states. The n5 bending fundamental has been studied for the
first time. In addition, the difference band n3 ¬ n4 has been
detected and analyzed. All the assigned transitions have been
fitted simultaneously by adopting a model Hamiltonian which takes
into account the vibration and rotation l-type resonances.
Rotational transitions in the ground and in bending excited states
reported in the literature have been included in the global
analysis. The set of 57 derived spectroscopic parameters reproduces
6130 infrared and 90 microwave and millimetre-wave transitions
satisfactorily with root mean square values of 5.3 ×10-4 cm-1, and
77 kHz, respectively.
18.The high-resolution infrared spectrum of deuterated acetylene
containing one 13C atom, 13C12CD2, has been recorded by Fourier
transform spectroscopy in the range 450 - 1700 cm-1. The n4 and n5
bending fundamental bands and a number of overtone, combination and
hot bands were identified. In total, 3210 rotation vibration
transitions were assigned to 27 bands involving bending states with
both v4 + v5 and |l4 + l5| up to 3. The ground state
and 13 vibrationally excited states were characterized, i.e. all
the l-vibrational components of the excited bending
manifolds with v4 + v5 up to 2, ( ), ( ), and (P
and F). Two simultaneous least-squares fits of all assigned
transitions have been performed, one considering transitions with
v4 + v5 up to 2, the other adding the transitions with v4 + v5 = 3.
The model Hamiltonian adopted for the analysis takes into account
the usual vibration and rotation l-type resonances within
each vibrational manifold and the Darling-Dennison anharmonic
resonance between and and between and . Two sets
of 33 and 42, respectively, spectroscopic parameters were derived.
They reproduce 1512 and 2450 assigned transitions with root mean
square values of 3.5 × 10-4 and 3.9 × 10-4 cm-1, respectively. The
transitions of four hot bands reaching the ( ) state were
fitted simultaneously to the effective upper state parameters.
19. The n4 fundamental band of CF379Br and CF381Br, present in
natural isotopic abundance, was investigated in the 8.3 mm region
by high resolution infrared spectroscopic techniques. Tuneable
diode laser spectra were recorded in the ranges 1202.5-1205.0 cm-1,
1208.0-1210.1 cm-1 and 1212.5-1214.5 cm-1 . The tuneable diode
laser spectra were obtained at the reduced temperature of 200 K and
in a free-jet expansion. The latter technique was used to reduce
spectral congestion, achieving a rotational temperature of about 50
K, with a resolution up to 0.0008 cm-1. A Fourier transform
infrared spectrum covering the entire spectral region of the n4
band, between 1190 and 1220 cm-1, was recorded at 298 K with a
resolution of 0.004 cm-1. The experimental wavenumbers from the
different spectroscopic techniques were combined to accomplish the
complete ro-vibrational analysis of n4. In total, 4651 transitions
were assigned to CF379Br, 4047 to CF381Br, with ; of these, 3171
for CF379Br and 2755 for CF381Br are from diode laser measurements.
The data of each isotopologue were analysed using the model
Hamiltonian for a degenerate vibrational state of a molecule of C3v
symmetry. The n4 band of both isotopologues resulted essentially
unperturbed but the l-resonance was found to be active
within the v4 = 1 state. Precise values of the vibrational
energy and of the ro-vibrational parameters of v4 = 1 for
CF379Br and CF381Br were obtained. The bromine isotopic splitting
amounts to 6.9 ´ 10-3 cm-1. In addition, the equilibrium geometry
and the harmonic force field were calculated ab initio using
the large-size basis set def2-QZVP in conjunction to the PBE0
functional.
20. The infrared spectrum of fully deuterated diacetylene below
1000 cm−1
L. Bizzocchi, F. Tamassia, C. Degli Esposti, L. Dore, M. Villa, and
E. Canè
Abstract
Diacetylene (HC4H) is the simplest polyyne and has been the subject
of several studies related
to technology, materials, supramolecular chemistry, non linear
optics. It has been detected in the
space and in the atmosphere of Titan. Moreover, it is a model
species to test sophisticated ab initio
calculations. In this paper we report the study of the infrared
spectrum of the rare isotopologue
DC4D below 1000 cm−1. The experiment has been performed by high
resolution Fourier transform
infrared spectroscopy. The 8 fundamental band, the 6 + 9, 7 + 8,
and 6 + 8 combination
bands and the 8 +9 −9 hot band have been observed and analysed,
providing a set of accurate
spectroscopic parameters. A global fit has also been performed in
order to take into account the
anharmonic resonance between the v3 = 1 and the v8 = v9 = 1 states.
The final results obtained
from the global fit show a good improvement in the spectroscopic
parameters for both the upper
and lower states.
21.
High resolution infrared and Raman spectra of 13C12CD2: the CD
stretching fundamentals and associated combination and hot
bands
G. Di Lonardo, L. Fusina, E. Canè, F. Tamassia, R. Z.
Martínez and D. Bermejo
Infrared and Raman spectra of mono 13C fully deuterated acetylene,
13C12CD2, have been recorded and analysed to obtain detailed
information on the CD stretching fundamentals n1 and n3 and
associated combination, overtone and hot bands. Infrared spectra
were recorded at a resolution ranging between 0.004 and 0.01 cm-1
in the region 1900 - 7800 cm-1. Sixty new bands involving the nu1
and nu3 C-D stretching modes, also associated with the nu4 and nu5
bending vibrations have been observed and analysed. In total, 5881
transitions have been assigned in the investigated spectral region.
In addition, the Q-branch of the nu2 fundamental was recorded using
inverse Raman spectroscopy, with an instrumental resolution of
about 0.003 cm-1. The transitions relative to each stretching mode,
i.e. the fundamental band, its first overtone, and associated hot
and combination bands involving bending states with v4+v5 up to 2
were fitted simultaneously. The usual Hamiltonian appropriate to a
linear molecule, including vibration and rotation
l-type and
the Darling-Dennison interaction between v4=2 and v5=2 levels
associated with the stretching states, was adopted for the
analysis. The standard deviation for each global fit is ≤ 0.0004
cm-1, of the same order of magnitude of the measurement precision.
Slightly improved parameters for the bending and the nu2
manifold have been also determined.
22. High resolution FTIR spectroscopy of HCFC-31 in the 950−1160
cm-1 region:rovibrational analysis and resonances in the ν4 , ν9
and ν5+ν6 bands of CH235ClF.
The FTIR spectrum of CH2ClF (natural isotopic mixture) was
investigated in the ν4, ν9 and ν5+ν6 band region between 950 and
1160 cm-1 at the resolution of 0.004 cm-1. The ν4 and ν5+ν6
vibrations of A' symmetry give rise to a/b hybrid bands with a
predominant a-type component. The ν9 vibration of A" symmetry,
expected with a c type band contour, shows an intense
Coriolis-induced parallel component (Ka = 0,Kc = 0) deriving from
mixing with the v4 = 1 vibrational state. The high resolution
spectra of ν9 and ν5+ν6 have been analyzed for the first time,
while the assignments of the ν4 band, previously investigated, have
been extended to higher J and Ka values in the b-type component.
The spectral analysis resulted in the identification of 1508, 809
and 349 transitions for the ν4, ν9 and ν5+ν6 bands of CH235ClF,
respectively. Besides the strong first-order a- and b-type Coriolis
resonances between ν4 and ν9, the ν5+ν6 vibration was found to
interact through a c-type Coriolis with the ν4 and 3ν6. High-order
anharmonic resonance (Ka = ±2) between ν4 and ν5+ν6 was also
established. All the assigned data were simultaneously fitted using
the Watson's A-reduction Hamiltonian
in the Ir representation and the relevant perturbation operators.
The model employed includes five types of resonances within the
tetrad ν4/ν9/ν5+ν6/3ν6. Α set of spectroscopic constants for ν4, ν9
and ν5+ν6 bands as well as parameters for the dark state 3ν6 and
seven coupling terms have been determined. The simulations
performed in different spectral regions satisfactorily reproduce
the experimental data.
My reaseach activity has been devoted since 1990 up to now in
the field of the high resolution molecular spectroscopy of gas
phase samples, in the UV-VIS, in the infrared and in the
microwave and millimeter wave regions.
The research in the infrared is mainly devoted to the
determination of molecular ro-vibrational spectroscopic parameters
from experimental rotational and ro-vibrational transitions.
The infrared spectra are recorded with a Bomem DA3.002 FTIR
spectrometer, which can achieve a maximum resolution of 0.004 cm-1.
A wide range of molecules, most of atmospheric and astrophysical
interest, have been studied : C2H2,C4H2, PD3, SbD3,SiH3D,
FClO3 (symmetric tops), SbHD2, C2H4 and aza-aromatic
compounds that can be classified as derivatives of purine and
pyrimidine, (asymmetric tops). In addition, test-molecules
which can be representative of some classes of compounds, i.e.
acetylene and benzene and naphthalene, are studied to test
theoretical models, like the local mode model, or different
redustion of the rotational or rovibrational
Hamiltonian.
The study of the spectra of many different isotopomers of
the acetylene, phophine, stibine, perchloryl
fluoride and aromatic compounds like benzene, naphtalene,
cyclopentadiene, anthracene and phenanthrene, provides
extensive information for the determination of the anharmonic force
field and molecular geometry. Sometimes, the IR spectra are
complemented by data obtained with the Raman technique and are
supported by ab initio calculations.
The analysis of experimental data is performed on the basis of
sophisticated theoretical models and requires the implementation of
adequate computer programs. It provides the energies of the
vibrational levels and the rotational and distortion
parameters.
The investigation of vibrationally excited states perturbed by
ro-vibrational interactions of Fermi or Coriolis type is of great
interest for the determination of the interaction parameters, which
characterise the dynamics of molecular processes related to the
energy transfer.
The reasearch in the UV-Visible region has been done by means of a
concave grating spectrograph, with a working resolution of 0.05
cm-1, operating in the laboratory. The absorption spectra are
recorded on plates and then transformed into digital files by means
of a high-resolution scanner. The spectroscopic parameters of the
electronic states involved in the transitions are determined from
the analysis of the spectra and are used together with infrared
data to derive the experimental anharmonicity constants.
From the rotational analysis of the microwave and millimeter wave
spectra of the aza-aromatic molecules the following
spectroscopic parameters have been derived: the molecular
constants in the electronic ground state, the molecular geometry,
the Stark coefficients and the dipole moments.