ABSTRACT
Pulsed slit-jet high resolution (up to 0.0009 cm(-1) FWHM) infrared diode laser spectra of CF(3)Br, with natural isotopic abundance, were obtained in the region around 9.2 microm at the rotational temperature of about 50 K. In addition, diode laser spectra at reduced temperature (200 K) were recorded. We present here the rovibrational analysis of the nu(1) fundamental in the range 1075-1090 cm(-1). The fine structure of many P(J) and R(J) clusters has been well resolved for the first time. The assignment of rovibrational transitions has been accomplished up to K = 27, J = 63 for CFBr and K = 33, J = 62 for CFBr. A total of 636 (CFBr) and 880 (CFBr) lines were used in the final fit and a very accurate set of molecular constants, including the quartic centrifugal distortion coefficients for the v(1) = 1 state of both the bromine isotopologues, was obtained. In addition, spectral features belonging to the nu(1) + nu(6)-nu(6) hot band were unambiguously identified and a set of spectroscopic parameters were determined.
ABSTRACT
The gas-phase infrared spectrum of cis-1-bromo-2-fluoroethene has been studied at low resolution in the range 200-6500 cm(-1), leading to a complete assignment of the fundamentals, except the lowest vibrational mode nu9 predicted at 167 cm(-1). The remaining vibrational structure has been mainly interpreted in terms of first overtone or two quanta combination bands. Isotopic (79/91)Br shift has been observed only in the nu8 fundamental. The equilibrium structure and the quadratic force field have been investigated theoretically at CCSD(T) level of theory employing Dunning's correlation consistent triple-zeta basis set. Cubic and semidiagonal quartic force field have been calculated using second-order Møller-Plesset perturbation theory and Ahlrich' split valence (SV) contracted basis set. After a minor scaled quantum mechanical (SQM) adjustment of the quadratic force constants, the vibrational analysis, based on the second-order perturbation theory, has been carried out with the calculated force constants.
Subject(s)
Ethylenes/chemistry , Hydrocarbons, Halogenated/chemistry , Gases , Molecular Structure , Quantum Theory , Spectroscopy, Fourier Transform InfraredABSTRACT
Protons and alpha particles of high linear energy transfer (LET) have shown an increased relative biological effectiveness (RBE) with respect to X/gamma rays for several cellular and molecular endpoints in different in vitro cell systems. To contribute to understanding the biochemical mechanisms involved in the increased effectiveness of high LET radiation, an extensive study has been designed. The present work reports the preliminary result of this study on two human tumoural cell lines, DLD1 and HCT116, (with different p53 status), which indicate that for these cell lines, p53 does not appear to take a part in the response to radiation induced DNA damage, suggesting an alternative p53-independent pathway and a cell biochemical mechanism dependent on the cell type.
Subject(s)
Alpha Particles , Cell Survival/radiation effects , Light , Protons , Tumor Suppressor Protein p53/radiation effects , Colorectal Neoplasms , Colorectal Neoplasms, Hereditary Nonpolyposis/pathology , Gene Expression Regulation, Neoplastic/radiation effects , Humans , Tumor Cells, Cultured , Tumor Suppressor Protein p53/geneticsABSTRACT
The vapor-phase infrared spectrum of monofluoroacetonitrile (CH(2)FCN) has been recorded at high resolution in the nu(4) band region (1363-1398 cm(-1)) using a tunable diode laser spectrometer. A detailed assignment of the rotational structure of the expected a-/b-hybrid band has been made for a-type transitions with K(a)
ABSTRACT
The gas-phase IR spectrum of the nu(2) (A(1), 1610.33 cm(-1)) band of the deuterated isotopomer of diazirine, D(2)CN(2), a three-membered ring compound which belongs to the molecular symmetry point group C(2v), has been studied at a resolution of about 0.005 cm(-1). This vibrational mode which can be approximately described as N&dbond;N stretching is widely perturbed. This is due to various interactions with the tetrad consisting of the binary combinations nu(6) + nu(7) (A(1)), nu(7) + nu(9) (A(2)), nu(5) + nu(6) (B(2)), and nu(5) + nu(9) (B(1)), which form a relatively isolated pentad together with nu(2) in the wavenumber region 1560-1610 cm(-1). A simultaneous upper state analysis of nu(2) from a pentad model including these resonances has been performed and a set of spectroscopic parameters has been obtained. Since the four combination bands of the pentad are dark states, only band centers could be determined; in addition for nu(5) + nu(9) and nu(7) + nu(9) also the term (B - C)/2 has been obtained. A number of Coriolis interaction constants and the vibrational resonance (with nu(6) + nu(7)) parameter have been calculated as well. Copyright 2001 Academic Press.
ABSTRACT
The diode laser spectrum of cis-1,2-CHF=CHF has been measured and analyzed in the nu4 fundamental region near 1016 cm(-1). This vibration of symmetry species A1 corresponds to the C-F symmetric stretching motion and gives rise to a strong b-type band. The rovibrational analysis, extended to the P, Q, and R branches, led to the identification of 2800 lines with J < or = 62, Ka < or = 18, Kc < or = 62. The assigned transitions free of major resonance contributions, fitted using Watson's A-reduction Hamiltonian in the Ir representation, yielded a set of spectroscopic parameters up to the quartic coefficients for the V4 = 1 state. Several perturbation effects occur throughout the band, mainly caused by the first-order c-type Coriolis interaction with the nu5 + nu11, vibrational state. Even though no transitions to the perturbing level were observed, the band orign and the rotational constants for the perturber were determined from a dyad model which includes the Coriolis interaction term.
Subject(s)
Ethylenes/chemistry , Spectrophotometry, Infrared/methods , Statistics as TopicABSTRACT
The gas-phase infrared spectrum of the nu(4) fundamental band of CH(2)(79)BrF was recorded in the 1010-1116 cm(-1) wavenumber region using a TDL spectrometer. In this first high-resolution investigation of the synthesized (79)Br isotopic form, more than 10 200 transitions of this a/b-hybrid band centered at 1068.5385 cm(-1) were assigned and, using the Watson's A-reduced Hamiltonian in the I(r)-representation, a reliable set of molecular constants for the excited state v(4) = 1 was determined. From ground state combination differences having rotational quantum numbers J and K(a) up to 97 and 21, respectively, improved and extended ground state rotational and centrifugal distortion constants were calculated as well. Comparison between the observed and calculated band intensities in appropriate regions of the spectrum gave an estimate of the transition dipole-moment ratio along the a and b axes as ||Deltaµ(a)/Deltaµ(b) || = 2.0 +/- 0.2, in agreement with the predicted theoretical value of 1.99. Copyright 2000 Academic Press.
ABSTRACT
cis-1-Chloro-2-fluoroethylene was synthesized, and the gas-phase infrared spectrum was investigated in the nu(4) band region between 1321-1350 cm(-1), at a resolution of about 0.002 cm(-1), employing a tunable diode-laser spectrometer. This vibration of symmetry species A' gives rise to an a/b-hybrid band, even though our analysis pointed out that the intensity of the a-type component is predominant. Most of the J and K structure was resolved in different subbranches, and the rovibrational analysis led to the assignment of about 1900 a-type lines with J
ABSTRACT
The spectra of CH2F37Cl (95% isotopically pure sample) have been recorded at high resolution with a tunable diode laser spectrometer in the regions 979-1030 and 1108-1136 cm-1. The spectral analysis allowed us to assign about 2000 lines (J
ABSTRACT
Diode laser spectra of CH2 F37 Cl (95% isotopically pure sample) have been recorded in the 9.4 µm region characterized by the nu4 fundamental. The spectral analysis allowed the assignment of more than 3700 transitions with J
