Search results for "hot band"
showing 10 items of 27 documents
High-Resolution Spectroscopy and Analysis of the nu(4) Bending Region of SF(6) near 615 cm(-1).
2001
The high-resolution Fourier transform spectrum of the nu(4) bending region of SF(6) near 615 cm(-1) has been recorded at 213 K. We were able to perform a simultaneous analysis of the nu(4) and nu(4) + nu(6) - nu(6) bands of the main isotopomer, namely (32)SF(6). This is the first detailed analysis of a hot band for this molecule. The nu(4) band of (34)SF(6) was also analyzed and the Q branch of the nu(4) band of (33)SF(6) was identified. In both cases we used the HTDS software developed in Dijon. Copyright 2001 Academic Press.
Vibrational spectrum of the spin crossover complex [Fe(phen)(2)(NCS)(2)] studied by IR and Raman spectroscopy, nuclear inelastic scattering and DFT c…
2006
The vibrational modes of the low-spin and high-spin isomers of the spin crossover complex [Fe(phen)(2)(NCS)(2)] (phen = 1,10-phenanthroline) have been measured by IR and Raman spectroscopy and by nuclear inelastic scattering. The vibrational frequencies and normal modes and the IR and Raman intensities have been calculated by density functional methods. The vibrational entropy difference between the two isomers, DeltaS(vib), which is--together with the electronic entropy difference DeltaS(el)--the driving force for the spin-transition, has been determined from the measured and from the calculated frequencies. The calculated difference (DeltaS(vib) = 57-70 J mol(-1) K(-1), depending on the m…
On the interpretation of the experimental Raman spectrum of β-eucryptite LiAlSiO4 from atomistic computer modeling
2000
Abstract The vibrational spectrum of β-eucryptite LiAlSiO4 with stuffed high quartz structure – commercially relevant for zero-expansion glass ceramics – was calculated by lattice energy minimization and diagonalization of the dynamical matrix using an ab initio based ion-pair shell model potential. A full symmetry analysis of the vibrational modes was carried out. Raman activity of vibrations was calculated under parameterization of individual polarizability factors for each type of interatomic bonds in β-eucryptite LiAlSiO4. Calculated vibrational energies agree with the experimental energies within ±2.3%. Agreement of calculated spectroscopic Raman intensities with experimental intensiti…
First analysis of the ν3+ν5 combination band of SF6 observed at Doppler-limited resolution and effective model for the ν3+ν5-ν5 hot band
2018
Abstract Sulfur hexafluoride is a greenhouse gas with a long lifetime in the atmosphere and an important tracer for air mass circulation atmospheric models. The IR spectrum of this heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 and v 5 = 1 vibrational states. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 168 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectra of the very weak ν 3 + ν 5 band near 1450 cm−1 have been recorded. Low temperature…
Observation and analysis of the SF6 ν2+ν4−ν5 band: Improved parameters for the v5= 1 state
2016
Abstract In this paper, we present the high resolution analysis of the weak ν 2 + ν 4 - ν 5 band of SF6 around 735 cm−1. The spectra were recorded on the AILES Beamline at the SOLEIL Synchrotron facility using a cryogenic multipass cell coupled to a Bruker 125HR spectrometer with a maximum resolution of 0.00102 cm−1. For this band, we worked with 4 mbar of SF6 at a temperature of 223 ± 2 K. The optical path length was fixed to 141 m and the spectrum recorded with 0.001 cm−1 of resolution. A new, cold spectrum of the ν 2 + ν 4 band was also collected at 153 K, 15-m path length, and 0.0015 cm−1 resolution. The analysis was performed by using the Dijon group XTDS and SPVIEW software, based on…
New measurements and global analysis of chloromethane in the region from 0 to 1800cm−1
2003
Abstract New high resolution Fourier transform spectra of pure 12CH335Cl and 12CH337Cl isotopomers of chloromethane have been recorded in Wuppertal covering the region from 600 to 3800 cm−1. New rotational transitions within the v2=1, v5=1, and v3=2 states have been measured at Lille. A first global analysis of the lower four band systems of the molecule (700–1800 cm−1) is reported. The model was based on an effective Hamiltonian and dipole moment expressed in terms of irreducible tensor operators. A common set of 125 effective hamiltonian parameters (sixth order) has been adjusted to fit simultaneously some 11 000 IR data for each of the isotopomers including 153 mm wave data for 12 CH3 35…
High resolution analysis of the SO2 spectrum in the 2600–2900cm−1 region: 2ν3, ν2+2ν3−ν2 and 2ν1+ν2 bands
2012
Abstract Infrared spectrum of the SO 2 molecule was recorded with high resolution in the 2600– 2900 cm − 1 region. Spectrum was recorded with the Fourier transform interferometer Bruker IFS-120 HR in Oulu (Finland) with the pressure of 111 Pa and the absorption path length of 163.2 m that allowed us to record 2 ν 3 and 2 ν 1 + ν 2 weak bands. The 2 ν 3 band discussed earlier by Lafferty et al., was re-analyzed, and considerably more information was extracted from the spectrum (more than 3800 transitions of the 2 ν 3 band were assigned in the experimental spectrum with maximum values of quantum numbers, J max . = 76 and K a max . = 26 ). On the basis of the procedure discussed in Ulenikov et…
A direct study of the vibrational bending effect in line mixing: The hot degenerate 1110 ← 0110 transition of CO2
1997
Abstract The study of the isotropiv Raman Q -branch of a hot band Π ← Π allows one to establish a direct connection between the vibration-rotation angular momentum coupling and the resulting spectra. Due to the l -doubling, the Q -branch is split into two subbranches characterized by either even or odd rotational quantum number j . The vibrational bending reduces the rotational transfer rates inside each of these subbranches by a factor of about two and induces an inter-subbranch coupling. The expected propensity rule towards conservation of the parity index for high rotational levels is well observed. Calculated spectra are in excellent agreement with CARS experiments for the v 1 + v 2 ← v…
Phonons in an inhomogeneous continuum: Vibrations of an embedded nanoparticle
2004
The spectrum of acoustic vibrational modes of an inhomogeneous elastic continuum are analyzed with application to a spherical nanoparticle embedded in an infinite glass block. The relationship of these modes to the discrete vibrational spectrum of a free sphere is studied. The vibrational modes of a sphere with a fixed surface are relevant in some situations. Comparisons are also made to calculations of mode frequency and damping based on complex valued frequency.
The Hot Bands of Methane between 5 and 10 μm
1996
Experimental line intensities of 1727 transitions arising from nine hot bands in the pentad-dyad system of methane are fitted to first and second order using the effective dipole moment expansion in the polyad scheme. The observed bands are nu3 - nu2, nu3 - nu4, nu1 - nu2, nu1 - nu4, 2nu4 - nu4, nu2 + nu4 - nu2, nu2 + nu4 - nu4, 2nu2 - nu2, and 2nu2 - nu4, and the intensities are obtained from long-path spectra recorded with the Fourier transform spectrometer located at Kitt Peak National Observatory. For the second order model, some of the 27 intensity parameters are not linearly independent, and so two methods (extrapolation and effective parameters) are proposed to model the intensities …