Viper Rattle - Academia.edu (original) (raw)
Papers by Viper Rattle
Infrared Physics, 1992
ABSTRACT In this work we carried out an infrared-infrared (IR-IR) double resonance (DR) study of ... more ABSTRACT In this work we carried out an infrared-infrared (IR-IR) double resonance (DR) study of methyl alcohol using a CO2 laser and a lead salt diode laser, in order to confirm previously proposed far-infrared (FIR) laser assignments for the 9P(34) and 9P(16) CO2 laser lines. For the 9P(34) CO2 laser line it is confirmed that the pump radiation excites the torsionally excited Q(125, 9) transition of methyl alcohol in agreement with the assignments proposed earlier. From the study it was noticed that due to the pump radiation, transitions which are not connected by dipole selection rules either to the lower or upper pumped level were also affected. Thus it appears that four-level IR-IR DR experiments are unlikely to provide useful information for transition assignments. The diode laser study was coupled with a recent spectroscopic study using a high resolution Fourier transform spectrometer to detect and identify hot band and perturbation allowed transitions in CH3OH.
In this work the Fourier transform far infrared spectrum of ('13)CH(,3)OH in the range 25-350... more In this work the Fourier transform far infrared spectrum of ('13)CH(,3)OH in the range 25-350 cm('-1) at a resolution of 0.004 cm('-1) is analyzed extensively. The b-type Q-branch origins obtained from extrapolation of observed R and Q branches are used to evaluate the semi -empirical Kirtman parameters in the vibrational ground state. The height of the internal rotational potential barrier V(,3) is found to be 373.75 cm('-1), and the V(,6) term to be -1.3 cm('-1). The assignments are presented in detail. In the infrared region, the Fourier transform spectra of the C-O stretching bands of ('12)CH(,3)OH and ('13)CH(,3)OH in the range 960-1079 cm('-1) and 950-1100 cm('-1), respectively, at 0.004 cm('-1) resolution, have been analyzed in detail. Assignments for the second excited torsional state of ('12)CH(,3)OH and for the ground, first, and second excited torsional states of ('13)CH(,3)OH are presented. The state-dependent infrared para...
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1997
In this paper, the relative intensities of far infrared transitions in the torsional ground state... more In this paper, the relative intensities of far infrared transitions in the torsional ground state of asymmetrically deuterated methanol CH,DOH are reported, using an internal axis method (IAM) theory. Relative intensities are presented for all possible strong band c-type Far Infrared (FIR) transitions upto K = 15 in the torsional vibrational ground state. Matrix elements for AK= f 1 transitions have been calculated upto the fourth excited torsional state. The calculations will be valuable in the assignments of far-infrared spectra and optically pumped far-infrared laser lines. The energy levels calculated will provide excellent data base for astrophysical detection of asymmetrically substituted methanol, which is of significant importance for the determination of parameters like the D/H ratio in the universe. 0 1997 Elsevier Science B.V.
International Journal of Infrared and Millimeter Waves, 1999
The high resolution Stark spectra of the singly deuterated methanol isotope, CH3OD, have been stu... more The high resolution Stark spectra of the singly deuterated methanol isotope, CH3OD, have been studied using the HCN laser with Stark fields up to approximately 60 000 V/cm. Numerous families of absorption lines have been observed in both parallel and perpendicular polarizations, resulting in the following assignments: with the 311 µm line – JK = 181 ? 180E2, ?t =
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1997
In this paper an internal axis method Hamiltonian model has been applied to evaluate the torsiona... more In this paper an internal axis method Hamiltonian model has been applied to evaluate the torsional-rotational molecular parameters of asymmetrically substituted methyl mercaptan (CH2DSH) using previously observed microwave transitions. The torsional barrier potential barrier functions V1, V2 and V3 have been refined. The observed microwave transition frequencies have also been fitted to an energy expansion model, which allowed accurate predictions of yet unobserved transition frequencies with microwave accuracy. These values are independent of the Hamiltonian model used and will prove valuable for astrophysical detection. The matrix elements between various torsional sub-levels upto the fourth excited torsional state in the ground vibrational state.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1998
ABSTRACT In this work, the Fourier transform far infrared (FTFIR) and infrared (IR) spectra of th... more ABSTRACT In this work, the Fourier transform far infrared (FTFIR) and infrared (IR) spectra of the completely deuterated methanol species CD3OD corresponding to the torsion–rotation band in the vibrational ground state and the CO stretch vibrational band, respectively, have been recorded and analyzed. From the IR analysis it has been possible to partially identify optically pumped FIR laser lines for four different CO2 laser pump systems from analytical considerations. In addition, laser Stark spectra have been studied using the HCN laser lines operating at 311 and 337 μm, in CD3OD. A number of Q-branch lines for K=11←10 E2n=0 assigned earlier and two strong R-branch transitions viz. R(8) and R(10) for K=7←6 A n=0 have been considered. The laser Stark spectrum for the R(10) transition has been reassigned from the previous work. The availability of the zero field frequencies with a precision of ±6 MHz from the high resolution FTFIR spectrum allowed the dipole moment of this important molecular species to be determined for the first time. The results will be useful for accurate intensity calculation and prediction of optically pumped FIR laser lines and astrophysically significant transitions.
Optics Communications, 1993
ABSTRACT In this work, analyses of the high resolution Fourier transform infrared (ir) spectra of... more ABSTRACT In this work, analyses of the high resolution Fourier transform infrared (ir) spectra of normal and C-13 methyl alcohol have been applied to find new assignments for four far infrared (fir) laser lines pumped by the 10R (18) CO2 laser line in 13CH3OH. Three of these FIR laser lines are proposed to terminate at levels which are strongly interacted by Coriolis resonance. A Coriolis interaction hamiltonian has been derived which explains the energy splitting between the interacting in-plane CH3-rocking and C-O stretching states. This is believed to be the first time that FIR laser lines are assigned to in-plane CH3-rocking state of C-13 substituted methanol.
Optics Communications, 1991
ABSTRACT In this work, the results of detailed spectroscopic analyses of the high-resolution Four... more ABSTRACT In this work, the results of detailed spectroscopic analyses of the high-resolution Fourier transform infrared (IR) C-O stretch and far-infrared (FIR) torsion-rotation bands of methyl alcohol are applied to assign and predict FIR laser lines optically pumped by a CO2 laser in the dense Q-branch region of the C-O stretch band. The assignments are supported by means of closed combination loops of accurately measured transition frequencies. For the predicted FIR lines, the frequencies are deduced with an accuracy of ±0.001 cm−1, which is at least an order of magnitude better than can be obtained from direct wavelength measurements. The IR and FIR spectroscopic data relevant to the assignments are included.
Optics Communications, 1994
High resolution Fourier infrared (IR) spectra corresponding to the OCD-bending, CO stretching and... more High resolution Fourier infrared (IR) spectra corresponding to the OCD-bending, CO stretching and CH2-rocking bands of methyl alcohol-D~ have been recorded in the range 815-1120 cm-t, at a resolution of 0.004 cm-t. Analysis of the OCD bending mode transitions yielded identification of quantum numbers involved for far infrared (FIR) laser lines optically pumped by the 10P (34) and 10P (46) CO2 laser lines. The observed wavenumbers for the OCD bending transitions relevant to the laser assignments are presented. The IR assignments are confirmed by forming close combination loops of observed R, P, and Q branch transitions. The results are in agreement with microwave (MW) analysis.
Journal of Molecular Spectroscopy, 2000
New millimeter-wave and microwave measurements for CH 3 OD have been combined with previous liter... more New millimeter-wave and microwave measurements for CH 3 OD have been combined with previous literature data and with an extended body of Fourier transform far-infrared observations in a full global analysis of the first two torsional states (v t ϭ 0 and 1) of the ground vibrational state. The fitted CH 3 OD data set contained 564 microwave and millimeter-wave lines and 4664 far-infrared lines, representing the most recent available information in the quantum number ranges J Յ 20 and K Յ 15. A 53-parameter converged global fit was achieved with an overall weighted standard deviation of 1.060, essentially to within the assigned measurement uncertainties of Ϯ100 kHz for almost all of the microwave and millimeter-wave lines and Ϯ6 MHz for the far-infrared lines. The new parameters for CH 3 OD are compared to previous results obtained for the 12 CH 3 OH, 13 CH 3 OH, and CD 3 OH isotopomers over the same quantum number ranges using the identical fitting program. Strong asymmetry-induced coupling between the accidentally near-degenerate 0E and Ϫ1E v t ϭ 0 substates is successfully modeled by the fit.
Journal of Molecular Spectroscopy, 1996
In this paper we report accurate measurements of microwave (MW) frequencies for nine different tr... more In this paper we report accurate measurements of microwave (MW) frequencies for nine different transitions in the first four torsional states in the ground vibrational state of O-18 substituted methanol, for a wide range of applied dc electric field. The Stark-shifted frequencies were measured with accuracies of about ±10 kHz. The results were analyzed to deduce accurate dipole moment values for the four torsional states involved. Substantial variation of dipole moment was observed as a function of the torsional state. The zero field frequencies have been also determined with much better precision than known before. The dipole moment values for the torsional ground state have been determined to be μa= 0.8992(8) and μb= 1.4226(3) D. The dipole moment value increases with torsional excitation. These values will be useful for the evaluation of relative intensities of interstellar microwave and millimeter wave transitions and optically pumped far infrared laser lines.
Journal of Molecular Spectroscopy, 1993
ABSTRACT In this paper, detailed analysis of the high-resolution Fourier transform spectra of the... more ABSTRACT In this paper, detailed analysis of the high-resolution Fourier transform spectra of the infrared (IR) C-O stretch and far-infrared (FIR) torsion-rotation bands of methyl alcohol has been applied to predict 30 potential FIR laser lines and to confirm previously proposed assignments of FIR emission lines optically pumped in the second and third excited torsional states of the C-O stretch mode. The combination loop closure technique provided accurate wavenumbers for the observed and predicted FIR laser transitions.
Journal of Molecular Spectroscopy, 1993
Journal of Molecular Spectroscopy, 1994
ABSTRACT In this work, the high-resolution infrared (IR) spectrum of 13C-substituted methyl alcoh... more ABSTRACT In this work, the high-resolution infrared (IR) spectrum of 13C-substituted methyl alcohol corresponding to the C-O stretch vibration and the far-infrared (FIR) spectrum corresponding to the torsional-rotational transitions have been recorded using a Fourier transform spectrometer. The results of detailed analyses of the spectra have been applied to propose new assignments of FIR laser lines pumped by the 9 P(34)CO2 laser line. These assignments involve highly perturbed levels in the first excited C-O stretch vibrational state. The assignments are supported by closed combination loops of accurately measured IR and FIR transitions. The analysis also yielded accurate frequencies for 17 potential FIR laser lines in [13C] methanol. The spectral data relevant to this work are presented. The FIR absorption spectroscopic study allowed us to evaluate the leading torsional-rotational molecular parameters for 13CH3OH in the vibrational ground state. The results of the high-resolution study will be useful for a precise model of the Hamiltonian for the excited C-O stretching state.
Journal of Molecular Spectroscopy, 1991
The laser Stark spectrum of fully deuterated methanol has been studied using the 337 and 311-mum ... more The laser Stark spectrum of fully deuterated methanol has been studied using the 337 and 311-mum lines of the HCN laser. Numerous families of absorption lines have been observed for both parallel and perpendicular polarizations up to 60 kV/cm. An extensive series of absorption lines observed at 311 mum has been assigned to the J = 11 to 19 members of the K = 11 <-- 10 E2 Q branch in the vt = 0 ground torsional state of CD3OD. An R-branch transition observed at 311 mum has been identified as the JK = 117 <-- 106A, vt = 0 transition. Three families of resonances observed at lambda = 337 mum are identified as JK = 183 <-- 172E1, vt = 0; JK = 173 <-- 164E1, vt = 1; and JK = 97 <-- 86A, vt = 0, transitions. Zero-field frequencies for all the assigned transitions are given with improved accuracy over those calculated from available molecular constants. For the Q-branch series, the branch origin and the series expansion coefficients are presented.
Infrared Physics, 1992
ABSTRACT In this work we carried out an infrared-infrared (IR-IR) double resonance (DR) study of ... more ABSTRACT In this work we carried out an infrared-infrared (IR-IR) double resonance (DR) study of methyl alcohol using a CO2 laser and a lead salt diode laser, in order to confirm previously proposed far-infrared (FIR) laser assignments for the 9P(34) and 9P(16) CO2 laser lines. For the 9P(34) CO2 laser line it is confirmed that the pump radiation excites the torsionally excited Q(125, 9) transition of methyl alcohol in agreement with the assignments proposed earlier. From the study it was noticed that due to the pump radiation, transitions which are not connected by dipole selection rules either to the lower or upper pumped level were also affected. Thus it appears that four-level IR-IR DR experiments are unlikely to provide useful information for transition assignments. The diode laser study was coupled with a recent spectroscopic study using a high resolution Fourier transform spectrometer to detect and identify hot band and perturbation allowed transitions in CH3OH.
In this work the Fourier transform far infrared spectrum of ('13)CH(,3)OH in the range 25-350... more In this work the Fourier transform far infrared spectrum of ('13)CH(,3)OH in the range 25-350 cm('-1) at a resolution of 0.004 cm('-1) is analyzed extensively. The b-type Q-branch origins obtained from extrapolation of observed R and Q branches are used to evaluate the semi -empirical Kirtman parameters in the vibrational ground state. The height of the internal rotational potential barrier V(,3) is found to be 373.75 cm('-1), and the V(,6) term to be -1.3 cm('-1). The assignments are presented in detail. In the infrared region, the Fourier transform spectra of the C-O stretching bands of ('12)CH(,3)OH and ('13)CH(,3)OH in the range 960-1079 cm('-1) and 950-1100 cm('-1), respectively, at 0.004 cm('-1) resolution, have been analyzed in detail. Assignments for the second excited torsional state of ('12)CH(,3)OH and for the ground, first, and second excited torsional states of ('13)CH(,3)OH are presented. The state-dependent infrared para...
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1997
In this paper, the relative intensities of far infrared transitions in the torsional ground state... more In this paper, the relative intensities of far infrared transitions in the torsional ground state of asymmetrically deuterated methanol CH,DOH are reported, using an internal axis method (IAM) theory. Relative intensities are presented for all possible strong band c-type Far Infrared (FIR) transitions upto K = 15 in the torsional vibrational ground state. Matrix elements for AK= f 1 transitions have been calculated upto the fourth excited torsional state. The calculations will be valuable in the assignments of far-infrared spectra and optically pumped far-infrared laser lines. The energy levels calculated will provide excellent data base for astrophysical detection of asymmetrically substituted methanol, which is of significant importance for the determination of parameters like the D/H ratio in the universe. 0 1997 Elsevier Science B.V.
International Journal of Infrared and Millimeter Waves, 1999
The high resolution Stark spectra of the singly deuterated methanol isotope, CH3OD, have been stu... more The high resolution Stark spectra of the singly deuterated methanol isotope, CH3OD, have been studied using the HCN laser with Stark fields up to approximately 60 000 V/cm. Numerous families of absorption lines have been observed in both parallel and perpendicular polarizations, resulting in the following assignments: with the 311 µm line – JK = 181 ? 180E2, ?t =
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1997
In this paper an internal axis method Hamiltonian model has been applied to evaluate the torsiona... more In this paper an internal axis method Hamiltonian model has been applied to evaluate the torsional-rotational molecular parameters of asymmetrically substituted methyl mercaptan (CH2DSH) using previously observed microwave transitions. The torsional barrier potential barrier functions V1, V2 and V3 have been refined. The observed microwave transition frequencies have also been fitted to an energy expansion model, which allowed accurate predictions of yet unobserved transition frequencies with microwave accuracy. These values are independent of the Hamiltonian model used and will prove valuable for astrophysical detection. The matrix elements between various torsional sub-levels upto the fourth excited torsional state in the ground vibrational state.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 1998
ABSTRACT In this work, the Fourier transform far infrared (FTFIR) and infrared (IR) spectra of th... more ABSTRACT In this work, the Fourier transform far infrared (FTFIR) and infrared (IR) spectra of the completely deuterated methanol species CD3OD corresponding to the torsion–rotation band in the vibrational ground state and the CO stretch vibrational band, respectively, have been recorded and analyzed. From the IR analysis it has been possible to partially identify optically pumped FIR laser lines for four different CO2 laser pump systems from analytical considerations. In addition, laser Stark spectra have been studied using the HCN laser lines operating at 311 and 337 μm, in CD3OD. A number of Q-branch lines for K=11←10 E2n=0 assigned earlier and two strong R-branch transitions viz. R(8) and R(10) for K=7←6 A n=0 have been considered. The laser Stark spectrum for the R(10) transition has been reassigned from the previous work. The availability of the zero field frequencies with a precision of ±6 MHz from the high resolution FTFIR spectrum allowed the dipole moment of this important molecular species to be determined for the first time. The results will be useful for accurate intensity calculation and prediction of optically pumped FIR laser lines and astrophysically significant transitions.
Optics Communications, 1993
ABSTRACT In this work, analyses of the high resolution Fourier transform infrared (ir) spectra of... more ABSTRACT In this work, analyses of the high resolution Fourier transform infrared (ir) spectra of normal and C-13 methyl alcohol have been applied to find new assignments for four far infrared (fir) laser lines pumped by the 10R (18) CO2 laser line in 13CH3OH. Three of these FIR laser lines are proposed to terminate at levels which are strongly interacted by Coriolis resonance. A Coriolis interaction hamiltonian has been derived which explains the energy splitting between the interacting in-plane CH3-rocking and C-O stretching states. This is believed to be the first time that FIR laser lines are assigned to in-plane CH3-rocking state of C-13 substituted methanol.
Optics Communications, 1991
ABSTRACT In this work, the results of detailed spectroscopic analyses of the high-resolution Four... more ABSTRACT In this work, the results of detailed spectroscopic analyses of the high-resolution Fourier transform infrared (IR) C-O stretch and far-infrared (FIR) torsion-rotation bands of methyl alcohol are applied to assign and predict FIR laser lines optically pumped by a CO2 laser in the dense Q-branch region of the C-O stretch band. The assignments are supported by means of closed combination loops of accurately measured transition frequencies. For the predicted FIR lines, the frequencies are deduced with an accuracy of ±0.001 cm−1, which is at least an order of magnitude better than can be obtained from direct wavelength measurements. The IR and FIR spectroscopic data relevant to the assignments are included.
Optics Communications, 1994
High resolution Fourier infrared (IR) spectra corresponding to the OCD-bending, CO stretching and... more High resolution Fourier infrared (IR) spectra corresponding to the OCD-bending, CO stretching and CH2-rocking bands of methyl alcohol-D~ have been recorded in the range 815-1120 cm-t, at a resolution of 0.004 cm-t. Analysis of the OCD bending mode transitions yielded identification of quantum numbers involved for far infrared (FIR) laser lines optically pumped by the 10P (34) and 10P (46) CO2 laser lines. The observed wavenumbers for the OCD bending transitions relevant to the laser assignments are presented. The IR assignments are confirmed by forming close combination loops of observed R, P, and Q branch transitions. The results are in agreement with microwave (MW) analysis.
Journal of Molecular Spectroscopy, 2000
New millimeter-wave and microwave measurements for CH 3 OD have been combined with previous liter... more New millimeter-wave and microwave measurements for CH 3 OD have been combined with previous literature data and with an extended body of Fourier transform far-infrared observations in a full global analysis of the first two torsional states (v t ϭ 0 and 1) of the ground vibrational state. The fitted CH 3 OD data set contained 564 microwave and millimeter-wave lines and 4664 far-infrared lines, representing the most recent available information in the quantum number ranges J Յ 20 and K Յ 15. A 53-parameter converged global fit was achieved with an overall weighted standard deviation of 1.060, essentially to within the assigned measurement uncertainties of Ϯ100 kHz for almost all of the microwave and millimeter-wave lines and Ϯ6 MHz for the far-infrared lines. The new parameters for CH 3 OD are compared to previous results obtained for the 12 CH 3 OH, 13 CH 3 OH, and CD 3 OH isotopomers over the same quantum number ranges using the identical fitting program. Strong asymmetry-induced coupling between the accidentally near-degenerate 0E and Ϫ1E v t ϭ 0 substates is successfully modeled by the fit.
Journal of Molecular Spectroscopy, 1996
In this paper we report accurate measurements of microwave (MW) frequencies for nine different tr... more In this paper we report accurate measurements of microwave (MW) frequencies for nine different transitions in the first four torsional states in the ground vibrational state of O-18 substituted methanol, for a wide range of applied dc electric field. The Stark-shifted frequencies were measured with accuracies of about ±10 kHz. The results were analyzed to deduce accurate dipole moment values for the four torsional states involved. Substantial variation of dipole moment was observed as a function of the torsional state. The zero field frequencies have been also determined with much better precision than known before. The dipole moment values for the torsional ground state have been determined to be μa= 0.8992(8) and μb= 1.4226(3) D. The dipole moment value increases with torsional excitation. These values will be useful for the evaluation of relative intensities of interstellar microwave and millimeter wave transitions and optically pumped far infrared laser lines.
Journal of Molecular Spectroscopy, 1993
ABSTRACT In this paper, detailed analysis of the high-resolution Fourier transform spectra of the... more ABSTRACT In this paper, detailed analysis of the high-resolution Fourier transform spectra of the infrared (IR) C-O stretch and far-infrared (FIR) torsion-rotation bands of methyl alcohol has been applied to predict 30 potential FIR laser lines and to confirm previously proposed assignments of FIR emission lines optically pumped in the second and third excited torsional states of the C-O stretch mode. The combination loop closure technique provided accurate wavenumbers for the observed and predicted FIR laser transitions.
Journal of Molecular Spectroscopy, 1993
Journal of Molecular Spectroscopy, 1994
ABSTRACT In this work, the high-resolution infrared (IR) spectrum of 13C-substituted methyl alcoh... more ABSTRACT In this work, the high-resolution infrared (IR) spectrum of 13C-substituted methyl alcohol corresponding to the C-O stretch vibration and the far-infrared (FIR) spectrum corresponding to the torsional-rotational transitions have been recorded using a Fourier transform spectrometer. The results of detailed analyses of the spectra have been applied to propose new assignments of FIR laser lines pumped by the 9 P(34)CO2 laser line. These assignments involve highly perturbed levels in the first excited C-O stretch vibrational state. The assignments are supported by closed combination loops of accurately measured IR and FIR transitions. The analysis also yielded accurate frequencies for 17 potential FIR laser lines in [13C] methanol. The spectral data relevant to this work are presented. The FIR absorption spectroscopic study allowed us to evaluate the leading torsional-rotational molecular parameters for 13CH3OH in the vibrational ground state. The results of the high-resolution study will be useful for a precise model of the Hamiltonian for the excited C-O stretching state.
Journal of Molecular Spectroscopy, 1991
The laser Stark spectrum of fully deuterated methanol has been studied using the 337 and 311-mum ... more The laser Stark spectrum of fully deuterated methanol has been studied using the 337 and 311-mum lines of the HCN laser. Numerous families of absorption lines have been observed for both parallel and perpendicular polarizations up to 60 kV/cm. An extensive series of absorption lines observed at 311 mum has been assigned to the J = 11 to 19 members of the K = 11 <-- 10 E2 Q branch in the vt = 0 ground torsional state of CD3OD. An R-branch transition observed at 311 mum has been identified as the JK = 117 <-- 106A, vt = 0 transition. Three families of resonances observed at lambda = 337 mum are identified as JK = 183 <-- 172E1, vt = 0; JK = 173 <-- 164E1, vt = 1; and JK = 97 <-- 86A, vt = 0, transitions. Zero-field frequencies for all the assigned transitions are given with improved accuracy over those calculated from available molecular constants. For the Q-branch series, the branch origin and the series expansion coefficients are presented.