Author: Martin Andreas Abel
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
Book Description
The electric charge distribution of molecules such as H2 and D2 is inversion-symmetric so that permanent dipole moments do not exist: such molecules are infrared-inactive. It is therefore interesting that gaseous, liquid, and solid hydrogen and its isotopes actually absorb infrared radiation, for example if gas densities are sufficiently high. The observed absorption arises from electric dipole moments induced by intermolecular interactions. It is of a supermolecular origin, due to binary (or higher-order) molecular complexes that may be transient (i.e., in a collisional encounter) or relatively stable (van-der-Waals molecule). Interaction-induced electric dipoles arise from the same mechanisms that generate the intermolecular forces: exchange forces, dispersion forces, and multipolar induction. Recently the induced dipole and potential energy surfaces of H2 pairs have been obtained by advanced quantum-chemical calculations. Interaction-induced absorption, more commonly called collision-induced absorption (CIA), by H2 pairs is an important opacity source in the atmospheres of various types of planets and cool stars, such as late stars, low-mass stars, brown dwarfs, certain white dwarfs, etc., and therefore of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra of their cores, mainly due to collision-induced absorption by collisional complexes of hydrogen and helium in the stellar atmospheres. Before proceeding to the frequencies and temperatures of interest it is good to check the new potential energy surface and induced dipole surface in all possible ways by comparison with existing isotopic laboratory measurements. Furthermore, the new potential energy surface is directly compared with previously available, well established intermolecular potential energy surfaces. The electric charge distributions of deuterium and hydrogen are very similar. The new potential energy and induced dipole surfaces were originally obtained to facilitate the computation of the collision-induced absorption of hydrogen. However, by replacing the rotovibrational wavefunctions of H2 with those of D2 the surfaces can also be used to calculate the collision-induced absorption of deuterium pairs, thereby probing them further. At the temperature of 298K existing measurements of the collision-induced absorption of D2--D2 gas are compared with our quantum scattering calculations in the D2 fundamental band (approximately 2,500cm−1 to 4,500cm−1). Furthermore, measurements of the collision-induced absorption of deuterium (D2) in the D2 first overtone band (about 5,250cm−1 to 7,250cm−1) at 201K are reported. These measurements are compared with ab initio calculations of the absorption spectra. Close agreement of measured and calculated spectra is seen.
Collision-induced Absorption by Molecular Deuterium (D2) in the Rototranslational Band, the Fundamental Band, and the First Overtone Band of
Author: Martin Andreas Abel
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
Book Description
The electric charge distribution of molecules such as H2 and D2 is inversion-symmetric so that permanent dipole moments do not exist: such molecules are infrared-inactive. It is therefore interesting that gaseous, liquid, and solid hydrogen and its isotopes actually absorb infrared radiation, for example if gas densities are sufficiently high. The observed absorption arises from electric dipole moments induced by intermolecular interactions. It is of a supermolecular origin, due to binary (or higher-order) molecular complexes that may be transient (i.e., in a collisional encounter) or relatively stable (van-der-Waals molecule). Interaction-induced electric dipoles arise from the same mechanisms that generate the intermolecular forces: exchange forces, dispersion forces, and multipolar induction. Recently the induced dipole and potential energy surfaces of H2 pairs have been obtained by advanced quantum-chemical calculations. Interaction-induced absorption, more commonly called collision-induced absorption (CIA), by H2 pairs is an important opacity source in the atmospheres of various types of planets and cool stars, such as late stars, low-mass stars, brown dwarfs, certain white dwarfs, etc., and therefore of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra of their cores, mainly due to collision-induced absorption by collisional complexes of hydrogen and helium in the stellar atmospheres. Before proceeding to the frequencies and temperatures of interest it is good to check the new potential energy surface and induced dipole surface in all possible ways by comparison with existing isotopic laboratory measurements. Furthermore, the new potential energy surface is directly compared with previously available, well established intermolecular potential energy surfaces. The electric charge distributions of deuterium and hydrogen are very similar. The new potential energy and induced dipole surfaces were originally obtained to facilitate the computation of the collision-induced absorption of hydrogen. However, by replacing the rotovibrational wavefunctions of H2 with those of D2 the surfaces can also be used to calculate the collision-induced absorption of deuterium pairs, thereby probing them further. At the temperature of 298K existing measurements of the collision-induced absorption of D2--D2 gas are compared with our quantum scattering calculations in the D2 fundamental band (approximately 2,500cm−1 to 4,500cm−1). Furthermore, measurements of the collision-induced absorption of deuterium (D2) in the D2 first overtone band (about 5,250cm−1 to 7,250cm−1) at 201K are reported. These measurements are compared with ab initio calculations of the absorption spectra. Close agreement of measured and calculated spectra is seen.
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
Book Description
The electric charge distribution of molecules such as H2 and D2 is inversion-symmetric so that permanent dipole moments do not exist: such molecules are infrared-inactive. It is therefore interesting that gaseous, liquid, and solid hydrogen and its isotopes actually absorb infrared radiation, for example if gas densities are sufficiently high. The observed absorption arises from electric dipole moments induced by intermolecular interactions. It is of a supermolecular origin, due to binary (or higher-order) molecular complexes that may be transient (i.e., in a collisional encounter) or relatively stable (van-der-Waals molecule). Interaction-induced electric dipoles arise from the same mechanisms that generate the intermolecular forces: exchange forces, dispersion forces, and multipolar induction. Recently the induced dipole and potential energy surfaces of H2 pairs have been obtained by advanced quantum-chemical calculations. Interaction-induced absorption, more commonly called collision-induced absorption (CIA), by H2 pairs is an important opacity source in the atmospheres of various types of planets and cool stars, such as late stars, low-mass stars, brown dwarfs, certain white dwarfs, etc., and therefore of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra of their cores, mainly due to collision-induced absorption by collisional complexes of hydrogen and helium in the stellar atmospheres. Before proceeding to the frequencies and temperatures of interest it is good to check the new potential energy surface and induced dipole surface in all possible ways by comparison with existing isotopic laboratory measurements. Furthermore, the new potential energy surface is directly compared with previously available, well established intermolecular potential energy surfaces. The electric charge distributions of deuterium and hydrogen are very similar. The new potential energy and induced dipole surfaces were originally obtained to facilitate the computation of the collision-induced absorption of hydrogen. However, by replacing the rotovibrational wavefunctions of H2 with those of D2 the surfaces can also be used to calculate the collision-induced absorption of deuterium pairs, thereby probing them further. At the temperature of 298K existing measurements of the collision-induced absorption of D2--D2 gas are compared with our quantum scattering calculations in the D2 fundamental band (approximately 2,500cm−1 to 4,500cm−1). Furthermore, measurements of the collision-induced absorption of deuterium (D2) in the D2 first overtone band (about 5,250cm−1 to 7,250cm−1) at 201K are reported. These measurements are compared with ab initio calculations of the absorption spectra. Close agreement of measured and calculated spectra is seen.
Collision-induced 1st Overtone Infrared Absorption Band of Deuterium
Author: Ching-Zhy Kuo
Publisher:
ISBN:
Category : Absorption spectra
Languages : en
Pages : 0
Book Description
Publisher:
ISBN:
Category : Absorption spectra
Languages : en
Pages : 0
Book Description
Pressure-induced Infrared Absorption of the Fundamental Band of Deuterium in D2-He and D2-Ne Mixtures at Different Temperatures
Author: Wilson Eric Russell
Publisher:
ISBN:
Category : Absorption spectra
Languages : en
Pages : 170
Book Description
Publisher:
ISBN:
Category : Absorption spectra
Languages : en
Pages : 170
Book Description
A Study of the Pressure-induced Fundamental Rotation-vibration Band of Deuterium in Deuterium-foreign Gas Mixtures at Room Temperature
Author: Pai, Siu Ting
Publisher: 1965.
ISBN:
Category : Deuterium
Languages : en
Pages : 146
Book Description
Publisher: 1965.
ISBN:
Category : Deuterium
Languages : en
Pages : 146
Book Description
Collision-induced Absorption in Gases
Author: Lothar Frommhold
Publisher:
ISBN: 9780521393454
Category : Science
Languages : en
Pages : 410
Book Description
This book reviews the theory and experiment of collision-induced absorption of infrared radiation in dense gases.
Publisher:
ISBN: 9780521393454
Category : Science
Languages : en
Pages : 410
Book Description
This book reviews the theory and experiment of collision-induced absorption of infrared radiation in dense gases.
Collision-Induced Absorption in Diatomic Molecule
Collision-induced Absorption in Diatomic Molecule/rare-gas Mixtures
Author: H. T. Yura
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 42
Book Description
A quantum mechanical calculation is given for collision-induced absorption in the infrared and far-infrared spectral regions for mixtures consisting of symmetrical diatomic molecules and rare-gas atoms. The induced moment consists of a short-range overlap term and a long-range quadrupole term. Near molecular transition lines, the quadrupole term gives the main contribution to the absorption, while in the far wings, the overlap term is dominant. The H2-He, H2-Ar, N2-Ar systems are considered, and an estimate is given of the absorption coefficient near 10 millimicrons for N2-N2 systems. (Author).
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 42
Book Description
A quantum mechanical calculation is given for collision-induced absorption in the infrared and far-infrared spectral regions for mixtures consisting of symmetrical diatomic molecules and rare-gas atoms. The induced moment consists of a short-range overlap term and a long-range quadrupole term. Near molecular transition lines, the quadrupole term gives the main contribution to the absorption, while in the far wings, the overlap term is dominant. The H2-He, H2-Ar, N2-Ar systems are considered, and an estimate is given of the absorption coefficient near 10 millimicrons for N2-N2 systems. (Author).
Physics Briefs
Collision- and Interaction-Induced Spectroscopy
Author: G.C. Tabisz
Publisher: Springer Science & Business Media
ISBN: 9401101833
Category : Science
Languages : en
Pages : 581
Book Description
Collision-or interaction-induced spectroscopy refers to radiative transitions, which are forbidden in free atoms or molecules, but which occur in clusters of interacting atoms or molecules. The most common phenomena are induced absorption, in the infrared region, and induced light scattering, which involves inelastic scattering of visible laser light. The particle interactions giving rise to the necessary induced dipole moments and polarizabilities are modelled at long range by multipole expansions; at short range, electron overlap and exchange mechanisms come into play. Information on atomic and molecular interactions and dynamics in dense media on a picosecond timescale may be drawn from the spectra. Collision-induced absorption in the infrared was discovered at the University of Toronto in 1949 by Crawford, Welsh and Locke who studied liquid O and N. Through the 1950s and 1960s, 2 2 experimental elucidation of the phenomenon, particularly in gases, continued and theoretical underpinnings were established. In the late 1960s, the related phenomenon of collision-induced light scattering was first observed in compressed inert gases. In 1978, an 'Enrico Fermi' Summer School was held at Varenna, Italy, under the directorship of J. Van Kranendonk. The lectures, there, reviewed activity from the previous two decades, during which the approach to the subject had not changed greatly. In 1983, a highly successful NATO Advanced Research Workshop was held at Bonas, France, under the directorship of G. Birnbaum. An important outcome of that meeting was the demonstration of the maturity and sophistication of current experimental and theoretical techniques.
Publisher: Springer Science & Business Media
ISBN: 9401101833
Category : Science
Languages : en
Pages : 581
Book Description
Collision-or interaction-induced spectroscopy refers to radiative transitions, which are forbidden in free atoms or molecules, but which occur in clusters of interacting atoms or molecules. The most common phenomena are induced absorption, in the infrared region, and induced light scattering, which involves inelastic scattering of visible laser light. The particle interactions giving rise to the necessary induced dipole moments and polarizabilities are modelled at long range by multipole expansions; at short range, electron overlap and exchange mechanisms come into play. Information on atomic and molecular interactions and dynamics in dense media on a picosecond timescale may be drawn from the spectra. Collision-induced absorption in the infrared was discovered at the University of Toronto in 1949 by Crawford, Welsh and Locke who studied liquid O and N. Through the 1950s and 1960s, 2 2 experimental elucidation of the phenomenon, particularly in gases, continued and theoretical underpinnings were established. In the late 1960s, the related phenomenon of collision-induced light scattering was first observed in compressed inert gases. In 1978, an 'Enrico Fermi' Summer School was held at Varenna, Italy, under the directorship of J. Van Kranendonk. The lectures, there, reviewed activity from the previous two decades, during which the approach to the subject had not changed greatly. In 1983, a highly successful NATO Advanced Research Workshop was held at Bonas, France, under the directorship of G. Birnbaum. An important outcome of that meeting was the demonstration of the maturity and sophistication of current experimental and theoretical techniques.