Carlos Eduardo Fellows - Academia.edu (original) (raw)

Papers by Carlos Eduardo Fellows

Journal of Molecular Spectroscopy, 1997

The Journal of chemical physics, Jan 7, 2014

In this article three vibrational bands of the electronic transition A(2)Σ(+)-X(2)Π of the N2O(+)... more In this article three vibrational bands of the electronic transition A(2)Σ(+)-X(2)Π of the N2O(+) radical (100-000, 000-001, and 001-001) are analysed through high resolution Fourier transform spectroscopy. The N2O(+) radical was produced by Penning ionization of N2O by colliding with metastable atoms of He(2(3)S) in a reaction chamber. The spectra was recorded in a spectral range of 24,500-30,000 cm(-1) and obtained from 200 coadded interferograms recorded at an apodized resolution of 0.08 cm(-1). Through a recursive way, the wavenumbers of the correspondent rotational transitions were reduced into molecular constants, improving the values previously reported. New values for the first vibrational energies ν₁', ν₃", and ν₃' are also obtained and compared with previous values reported in the literature.

Revista Mexicana De Fisica, 1989

Author Institution: Laboratorio de Espectroscopia e Laser, Instituto de Fisica, Universidade Fede... more Author Institution: Laboratorio de Espectroscopia e Laser, Instituto de Fisica, Universidade Federal Fluminense, Niteroi, Rio de Janeiro, Brazil

Journal of Quantitative Spectroscopy and Radiative Transfer, 2020

Abstract In this article, a new study of the 12C16O + First Negative system (B 2 Σ + → X 2 Σ + ),... more Abstract In this article, a new study of the 12C16O + First Negative system (B 2 Σ + → X 2 Σ + ), is performed both theoretically and experimentally. From an experimental point of view, high-resolution Fourier transform spectroscopy in the ultraviolet region was used. On the theoretical side, ab initio electronic energies were calculated employing the state-averaged multiconfiguration self-consistent field (MCSCF) method, followed by the icMRCI/AV6Z level of theory with Davidson modification. Through these two analyses, theoretical and experimental, values for the spectroscopic constants, potential energy curves, and parameters concerning the transition are presented. The results, both theoretical and experimental, obtained in this work are compared with values obtained in previous works, pointing out certain discrepancies with more recent works and providing new and improved values for the band origins of this transition.

Journal of The Optical Society of America B-optical Physics, 1984

ABSTRACT An analysis of a modified electrode geometry for pulsed gas-laser excitation circuits, g... more ABSTRACT An analysis of a modified electrode geometry for pulsed gas-laser excitation circuits, generating shorter excitation pulses than those normally obtained, is reported. Results from an atmospheric N2 laser obtained with this electrode geometry are compared with others available in the literature.

Chemical Physics Letters, 1999

The visible fluorescence produced by vacuum-ultraviolet photodissociation of acetylene, particula... more The visible fluorescence produced by vacuum-ultraviolet photodissociation of acetylene, particularly through the Rydberg states, has been studied in a gas-flow system using synchrotron radiation as a light source between 154 and 60 nm and an original light collection device. Excitation of the Rydberg states below the first IP reveals only the C H product by 2ĩ ts AX continuum emission spectrum between 330 and 900 nm. Evolution in the emission spectral profile as a function of excitation wavelength has been observed, indicative of specific internal distribution favoring the bending levels of the à 2 state of C H. A new assignment of the Rydberg series converging to the first excited state A A of the cation is proposed 2 g on the basis of recent experimental and theoretical characterization of this state and leads to an approximate value of the Ž y1. CC stretching frequency of the cation n f 1500 cm .

Applied Physics B Laser and Optics, 1994

ABSTRACT This work reports the role some additives have in pre-ionizing a N2 TE UV laser (337.1 n... more ABSTRACT This work reports the role some additives have in pre-ionizing a N2 TE UV laser (337.1 nm). The modifications in both stimulated radiation characteristics and excitation-pulse period prove the different ionizing power of each element. The laser operating without a pre-ionizing wire device and with N2 plus different additives was able to generate pulses with a temporal width of the same order than those obtained when it was operating with N2 and a pre-ionizing wire device. Also, a relation between ionization efficiency and interelectrode distance has been established allowing the prediction of conditions for optimum laser-pulse width generation.

Molecular Physics, 2021

The Simulated Annealing (SA) method is here first adopted to retrieve the molecular constants use... more The Simulated Annealing (SA) method is here first adopted to retrieve the molecular constants used to fit wavenumbers into a model, from a vibrational band of the electronic transition A of the N O radical, 000–000, starting from a set of molecular constants obtained in a previous work, and varying their values within a range in order to mimic an error in each one parameter used. The SA calculations have been carried out following the proposal of Vanderbilt and Louie for performing a minimisation of an objective function where the parameters are continuous variables whose values can vary. Through SA, the 280 experimentally wavenumbers from the previous work were reduced using a Hamiltonian model and new molecular constants obtained. A comparison among the results obtained through a nonlinear deterministic model and the retrieved values obtained using the SA shows that the simulated annealing can be considered as a very strong method for molecular constants determination. Second, intending to test the SA method in a direct fit to obtain the molecular constants, the 142 wavenumbers from the 001–001 band A electronic transition of the N O were studied in this work and the molecular constants analysed. GRAPHICAL ABSTRACT

Applied Physics B, 2011

Nitrogen laser performance with TE configuration and wedge electrodes is analyzed with background... more Nitrogen laser performance with TE configuration and wedge electrodes is analyzed with background ionization in the laser discharge channel by alpha particles at a low exposition rate. With the bias ionization, the laser power presents two peaks as a function of gas pressure, with one at the normal low pressure, without bias ionization, and the other at high pressure generated

Journal of Molecular Spectroscopy, 1997

Biofuels Production and Processing Technology, 2017

International Journal of Oil, Gas and Coal Technology, 2017

This paper is related with the use of palm oil and palm biodiesel mixed with diesel in different ... more This paper is related with the use of palm oil and palm biodiesel mixed with diesel in different percentages in a stationary engine. It presented the steps for obtaining biodiesel from palm oil and the characterisation of palm oil and palm biodiesel. It also shows the results for performance and emissions of using palm oil and palm biodiesel in a stationary engine. It was concluded that palm oil can be successfully applied in compression ignition engine blending with diesel up to 20% of palm oil. Palm oil can also be converted in biodiesel and used in compression ignition engines neat or blended with diesel in any proportion. The use of neat palm biodiesel is not recommended in cold weather conditions due to its low pour point. The use of palm oil and palm biodiesel in power generation lead to the concepts of sustainability, by the use of a raw material that contributes to CO2 absorption. [Received: September 23, 2015; Accepted: July 24, 2016]

Journal of Quantitative Spectroscopy and Radiative Transfer, 2020

Abstract In this work a new analysis of the 010-010 and 000–010 bands in the A 2 Σ + - X2Π electr... more Abstract In this work a new analysis of the 010-010 and 000–010 bands in the A 2 Σ + - X2Π electronic transition of the N2O + molecule is performed by high resolution Fourier transform spectroscopy. Two sets of spectra of the N2O + molecule at different temperatures are analysed, one at 30 K and the other at 340 K approximately, which made possible an unambiguous assignment of the spectral lines. Due to this fact and from a “natural” advantage of the Fourier transform spectroscopy since, being an interferential spectrometry, the obtained spectrum provides absolute wavenumbers and no further calibration is required, the more accurate wavenumber allowed new and improved molecular constants and band origins, making it possible to obtain more reliable values for previously reported molecular constants. With these new constants, a new set of spin-vibronic term values was determined and compared to the values already reported in the literature.

Physical Chemistry Chemical Physics, 2011

Methane photolysis has been performed at the two Vacuum UltraViolet (VUV) wavelengths, 121.6 nm a... more Methane photolysis has been performed at the two Vacuum UltraViolet (VUV) wavelengths, 121.6 nm and 118.2 nm, via a spectrally pure laser pump-probe technique. The first photon is used to dissociate methane (either at 121.6 nm or at 118.2 nm) and the second one is used to ionise the CH(2) and CH(3) fragments. The radical products, CH(3)(X), CH(2)(X), CH(2)(a) and C((1)D), have been selectively probed by mass spectrometry. In order to quantify the fragment quantum yields from the mass spectra, the photoionisation cross sections have been carefully evaluated for the CH(2) and CH(3) radicals, in two steps: first, theoretical ab initio approaches have been used in order to determine the pure electronic photoionisation cross sections of CH(2)(X) and CH(2)(a), and have been rescaled with respect to the measured absolute photoionisation cross section of the CH(3)(X) radical. In a second step, in order to take into account the substantial vibrational energy deposited in the CH(3)(X) and CH(2)(a) radicals, the variation of their cross sections near threshold has been simulated by introducing the pertinent Franck-Condon overlaps between neutral and cation species. By adding the interpolated values of CH quantum yields measured by Rebbert and Ausloos [J. Photochem., 1972, 1, 171-176], a complete set of fragment quantum yields has been derived for the methane photodissociation at 121.6 nm, with carefully evaluated 1σ uncertainties: Φ[CH(3)(X)] = 0.42 ± 0.05, Φ[CH(2)(a)] = 0.48 ± 0.05, Φ[CH(2)(X)] = 0.03 ± 0.08, Φ[CH(X)] = 0.07 ± 0.01. These new data have been measured independently of the H atom fragment quantum yield, subject to many controversies in the literature. From our results, we evaluate Φ(H) = 0.55 ± 0.17 at 121.6 nm. The quantum yields for the photolysis at 118.2 nm differ notably from those measured at 121.6 nm, with a substantial production of the CH(2)(X) fragment: Φ[CH(3)(X)] = 0.26 ± 0.04, Φ[CH(2)(a)] = 0.17 ± 0.05, Φ[CH(2)(X)] = 0.48 ± 0.06, Φ[CH(X)] = 0.09 ± 0.01, Φ(H) = 1.31 ± 0.13. These new data should bring reliable and essential inputs for the photochemical models of the Titan atmosphere.

Molecular Physics, 1988

ABSTRACT The X1Sigma+ ground electronic state of the NaLi molecule has been studied by laser indu... more ABSTRACT The X1Sigma+ ground electronic state of the NaLi molecule has been studied by laser induced fluorescence recorded by a Fourier transform spectrometer. Ground state molecular constants and the derived rotationless potential energy curve up to v'' = 20 are reported. Improvements made in the heating system of the heat-pipe oven in order to produce NaLi molecules are also described. Comparison with previous work, theoretical and experimental, is made.

Journal of Molecular Spectroscopy, 1997

The exchange energy in the long-range near-dissociation region is analyzed for the ground electro... more The exchange energy in the long-range near-dissociation region is analyzed for the ground electronic states of homo- and heteronuclear alkali diatomic molecules. The analysis is based on the use of the functional form Ae-ar to represent this exchange term. A period effect is observed in the values of both parameters and the exponent parameter a appears to approach an asymptotic limit for the heavier molecules. The results obtained in this study also suggest that some care must be taken in using even this function to represent the exchange energy. Copyright 1997 Academic Press. Copyright 1997Academic Press

Remote Sensing, 2022

We report on the first aerosol profiling campaign in the Paraíba valley, a hub connecting the reg... more We report on the first aerosol profiling campaign in the Paraíba valley, a hub connecting the region between the two largest Brazilian metropolitan areas, São Paulo and Rio de Janeiro. São Paulo Sanitation Technology Company (CETESB) air quality and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data show homogeneous behavior of the atmosphere throughout the region. A more detailed description of the particulate material in the local atmosphere, including its temporal dependence, can be obtained by using ground-based lidars. Measurements were carried out with a backscatter lidar system in two industrial cities, Volta Redonda and Lorena. The aerosol backscatter profiles present several peaks at different altitudes, indicating the presence of aerosol in several atmospheric layers. In addition, The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) air-mass back-trajectories indicate a possible detection of long-range aerosol transported fro...

Conference on Lasers and Electro-Optics, 1986

Journal of Molecular Spectroscopy, 2010

This paper is concerned with an analysis of the high resolution spectra of the fundamental v 2 ba... more This paper is concerned with an analysis of the high resolution spectra of the fundamental v 2 band of both 15 NH 2 D and 15 ND 2 H. Absorption spectra were recorded in the 690-1150 cm -1 region with a Fourier transform spectrometer. The assignment of the ν 2 band transitions and a theoretical analysis of the vibration-inversion-rotation energy levels involved with these transitions were performed for both species. The first determination of the spectroscopic constants relevant to the symmetric and antisymmetric upper inversion substates of the fundamental ν 2 band was carried out.

Journal of Molecular Spectroscopy, 1997

The Journal of chemical physics, Jan 7, 2014

In this article three vibrational bands of the electronic transition A(2)Σ(+)-X(2)Π of the N2O(+)... more In this article three vibrational bands of the electronic transition A(2)Σ(+)-X(2)Π of the N2O(+) radical (100-000, 000-001, and 001-001) are analysed through high resolution Fourier transform spectroscopy. The N2O(+) radical was produced by Penning ionization of N2O by colliding with metastable atoms of He(2(3)S) in a reaction chamber. The spectra was recorded in a spectral range of 24,500-30,000 cm(-1) and obtained from 200 coadded interferograms recorded at an apodized resolution of 0.08 cm(-1). Through a recursive way, the wavenumbers of the correspondent rotational transitions were reduced into molecular constants, improving the values previously reported. New values for the first vibrational energies ν₁', ν₃", and ν₃' are also obtained and compared with previous values reported in the literature.

Revista Mexicana De Fisica, 1989

Author Institution: Laboratorio de Espectroscopia e Laser, Instituto de Fisica, Universidade Fede... more Author Institution: Laboratorio de Espectroscopia e Laser, Instituto de Fisica, Universidade Federal Fluminense, Niteroi, Rio de Janeiro, Brazil

Journal of Quantitative Spectroscopy and Radiative Transfer, 2020

Abstract In this article, a new study of the 12C16O + First Negative system (B 2 Σ + → X 2 Σ + ),... more Abstract In this article, a new study of the 12C16O + First Negative system (B 2 Σ + → X 2 Σ + ), is performed both theoretically and experimentally. From an experimental point of view, high-resolution Fourier transform spectroscopy in the ultraviolet region was used. On the theoretical side, ab initio electronic energies were calculated employing the state-averaged multiconfiguration self-consistent field (MCSCF) method, followed by the icMRCI/AV6Z level of theory with Davidson modification. Through these two analyses, theoretical and experimental, values for the spectroscopic constants, potential energy curves, and parameters concerning the transition are presented. The results, both theoretical and experimental, obtained in this work are compared with values obtained in previous works, pointing out certain discrepancies with more recent works and providing new and improved values for the band origins of this transition.

Journal of The Optical Society of America B-optical Physics, 1984

ABSTRACT An analysis of a modified electrode geometry for pulsed gas-laser excitation circuits, g... more ABSTRACT An analysis of a modified electrode geometry for pulsed gas-laser excitation circuits, generating shorter excitation pulses than those normally obtained, is reported. Results from an atmospheric N2 laser obtained with this electrode geometry are compared with others available in the literature.

Chemical Physics Letters, 1999

The visible fluorescence produced by vacuum-ultraviolet photodissociation of acetylene, particula... more The visible fluorescence produced by vacuum-ultraviolet photodissociation of acetylene, particularly through the Rydberg states, has been studied in a gas-flow system using synchrotron radiation as a light source between 154 and 60 nm and an original light collection device. Excitation of the Rydberg states below the first IP reveals only the C H product by 2ĩ ts AX continuum emission spectrum between 330 and 900 nm. Evolution in the emission spectral profile as a function of excitation wavelength has been observed, indicative of specific internal distribution favoring the bending levels of the à 2 state of C H. A new assignment of the Rydberg series converging to the first excited state A A of the cation is proposed 2 g on the basis of recent experimental and theoretical characterization of this state and leads to an approximate value of the Ž y1. CC stretching frequency of the cation n f 1500 cm .

Applied Physics B Laser and Optics, 1994

ABSTRACT This work reports the role some additives have in pre-ionizing a N2 TE UV laser (337.1 n... more ABSTRACT This work reports the role some additives have in pre-ionizing a N2 TE UV laser (337.1 nm). The modifications in both stimulated radiation characteristics and excitation-pulse period prove the different ionizing power of each element. The laser operating without a pre-ionizing wire device and with N2 plus different additives was able to generate pulses with a temporal width of the same order than those obtained when it was operating with N2 and a pre-ionizing wire device. Also, a relation between ionization efficiency and interelectrode distance has been established allowing the prediction of conditions for optimum laser-pulse width generation.

Molecular Physics, 2021

The Simulated Annealing (SA) method is here first adopted to retrieve the molecular constants use... more The Simulated Annealing (SA) method is here first adopted to retrieve the molecular constants used to fit wavenumbers into a model, from a vibrational band of the electronic transition A of the N O radical, 000–000, starting from a set of molecular constants obtained in a previous work, and varying their values within a range in order to mimic an error in each one parameter used. The SA calculations have been carried out following the proposal of Vanderbilt and Louie for performing a minimisation of an objective function where the parameters are continuous variables whose values can vary. Through SA, the 280 experimentally wavenumbers from the previous work were reduced using a Hamiltonian model and new molecular constants obtained. A comparison among the results obtained through a nonlinear deterministic model and the retrieved values obtained using the SA shows that the simulated annealing can be considered as a very strong method for molecular constants determination. Second, intending to test the SA method in a direct fit to obtain the molecular constants, the 142 wavenumbers from the 001–001 band A electronic transition of the N O were studied in this work and the molecular constants analysed. GRAPHICAL ABSTRACT

Applied Physics B, 2011

Nitrogen laser performance with TE configuration and wedge electrodes is analyzed with background... more Nitrogen laser performance with TE configuration and wedge electrodes is analyzed with background ionization in the laser discharge channel by alpha particles at a low exposition rate. With the bias ionization, the laser power presents two peaks as a function of gas pressure, with one at the normal low pressure, without bias ionization, and the other at high pressure generated

Journal of Molecular Spectroscopy, 1997

Biofuels Production and Processing Technology, 2017

International Journal of Oil, Gas and Coal Technology, 2017

This paper is related with the use of palm oil and palm biodiesel mixed with diesel in different ... more This paper is related with the use of palm oil and palm biodiesel mixed with diesel in different percentages in a stationary engine. It presented the steps for obtaining biodiesel from palm oil and the characterisation of palm oil and palm biodiesel. It also shows the results for performance and emissions of using palm oil and palm biodiesel in a stationary engine. It was concluded that palm oil can be successfully applied in compression ignition engine blending with diesel up to 20% of palm oil. Palm oil can also be converted in biodiesel and used in compression ignition engines neat or blended with diesel in any proportion. The use of neat palm biodiesel is not recommended in cold weather conditions due to its low pour point. The use of palm oil and palm biodiesel in power generation lead to the concepts of sustainability, by the use of a raw material that contributes to CO2 absorption. [Received: September 23, 2015; Accepted: July 24, 2016]

Journal of Quantitative Spectroscopy and Radiative Transfer, 2020

Abstract In this work a new analysis of the 010-010 and 000–010 bands in the A 2 Σ + - X2Π electr... more Abstract In this work a new analysis of the 010-010 and 000–010 bands in the A 2 Σ + - X2Π electronic transition of the N2O + molecule is performed by high resolution Fourier transform spectroscopy. Two sets of spectra of the N2O + molecule at different temperatures are analysed, one at 30 K and the other at 340 K approximately, which made possible an unambiguous assignment of the spectral lines. Due to this fact and from a “natural” advantage of the Fourier transform spectroscopy since, being an interferential spectrometry, the obtained spectrum provides absolute wavenumbers and no further calibration is required, the more accurate wavenumber allowed new and improved molecular constants and band origins, making it possible to obtain more reliable values for previously reported molecular constants. With these new constants, a new set of spin-vibronic term values was determined and compared to the values already reported in the literature.

Physical Chemistry Chemical Physics, 2011

Methane photolysis has been performed at the two Vacuum UltraViolet (VUV) wavelengths, 121.6 nm a... more Methane photolysis has been performed at the two Vacuum UltraViolet (VUV) wavelengths, 121.6 nm and 118.2 nm, via a spectrally pure laser pump-probe technique. The first photon is used to dissociate methane (either at 121.6 nm or at 118.2 nm) and the second one is used to ionise the CH(2) and CH(3) fragments. The radical products, CH(3)(X), CH(2)(X), CH(2)(a) and C((1)D), have been selectively probed by mass spectrometry. In order to quantify the fragment quantum yields from the mass spectra, the photoionisation cross sections have been carefully evaluated for the CH(2) and CH(3) radicals, in two steps: first, theoretical ab initio approaches have been used in order to determine the pure electronic photoionisation cross sections of CH(2)(X) and CH(2)(a), and have been rescaled with respect to the measured absolute photoionisation cross section of the CH(3)(X) radical. In a second step, in order to take into account the substantial vibrational energy deposited in the CH(3)(X) and CH(2)(a) radicals, the variation of their cross sections near threshold has been simulated by introducing the pertinent Franck-Condon overlaps between neutral and cation species. By adding the interpolated values of CH quantum yields measured by Rebbert and Ausloos [J. Photochem., 1972, 1, 171-176], a complete set of fragment quantum yields has been derived for the methane photodissociation at 121.6 nm, with carefully evaluated 1σ uncertainties: Φ[CH(3)(X)] = 0.42 ± 0.05, Φ[CH(2)(a)] = 0.48 ± 0.05, Φ[CH(2)(X)] = 0.03 ± 0.08, Φ[CH(X)] = 0.07 ± 0.01. These new data have been measured independently of the H atom fragment quantum yield, subject to many controversies in the literature. From our results, we evaluate Φ(H) = 0.55 ± 0.17 at 121.6 nm. The quantum yields for the photolysis at 118.2 nm differ notably from those measured at 121.6 nm, with a substantial production of the CH(2)(X) fragment: Φ[CH(3)(X)] = 0.26 ± 0.04, Φ[CH(2)(a)] = 0.17 ± 0.05, Φ[CH(2)(X)] = 0.48 ± 0.06, Φ[CH(X)] = 0.09 ± 0.01, Φ(H) = 1.31 ± 0.13. These new data should bring reliable and essential inputs for the photochemical models of the Titan atmosphere.

Molecular Physics, 1988

ABSTRACT The X1Sigma+ ground electronic state of the NaLi molecule has been studied by laser indu... more ABSTRACT The X1Sigma+ ground electronic state of the NaLi molecule has been studied by laser induced fluorescence recorded by a Fourier transform spectrometer. Ground state molecular constants and the derived rotationless potential energy curve up to v'' = 20 are reported. Improvements made in the heating system of the heat-pipe oven in order to produce NaLi molecules are also described. Comparison with previous work, theoretical and experimental, is made.

Journal of Molecular Spectroscopy, 1997

The exchange energy in the long-range near-dissociation region is analyzed for the ground electro... more The exchange energy in the long-range near-dissociation region is analyzed for the ground electronic states of homo- and heteronuclear alkali diatomic molecules. The analysis is based on the use of the functional form Ae-ar to represent this exchange term. A period effect is observed in the values of both parameters and the exponent parameter a appears to approach an asymptotic limit for the heavier molecules. The results obtained in this study also suggest that some care must be taken in using even this function to represent the exchange energy. Copyright 1997 Academic Press. Copyright 1997Academic Press

Remote Sensing, 2022

We report on the first aerosol profiling campaign in the Paraíba valley, a hub connecting the reg... more We report on the first aerosol profiling campaign in the Paraíba valley, a hub connecting the region between the two largest Brazilian metropolitan areas, São Paulo and Rio de Janeiro. São Paulo Sanitation Technology Company (CETESB) air quality and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data show homogeneous behavior of the atmosphere throughout the region. A more detailed description of the particulate material in the local atmosphere, including its temporal dependence, can be obtained by using ground-based lidars. Measurements were carried out with a backscatter lidar system in two industrial cities, Volta Redonda and Lorena. The aerosol backscatter profiles present several peaks at different altitudes, indicating the presence of aerosol in several atmospheric layers. In addition, The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) air-mass back-trajectories indicate a possible detection of long-range aerosol transported fro...

Conference on Lasers and Electro-Optics, 1986

Journal of Molecular Spectroscopy, 2010

This paper is concerned with an analysis of the high resolution spectra of the fundamental v 2 ba... more This paper is concerned with an analysis of the high resolution spectra of the fundamental v 2 band of both 15 NH 2 D and 15 ND 2 H. Absorption spectra were recorded in the 690-1150 cm -1 region with a Fourier transform spectrometer. The assignment of the ν 2 band transitions and a theoretical analysis of the vibration-inversion-rotation energy levels involved with these transitions were performed for both species. The first determination of the spectroscopic constants relevant to the symmetric and antisymmetric upper inversion substates of the fundamental ν 2 band was carried out.