Band Contour Analysis Research Articles

The 3ν 3 overtone intensities and vibrational anharmonicity constants of UF 6 and PuF 6

We report the 3ν 3 band contour analyses of UF 6 and PuF 6. The transition wavenumbers and the absolute vibrational intensities are determined, and systematics of the overtone intensities among SF 6, UF 6, and PuF 6 are discussed.

FTIR spectrum of benzene in a supersonic expansion

The 700 and 3050 cm −1 region of benzene seeded in argon is studied using Fourier-transform infrared absorption spectroscopy. Analysis of the sequence band structure in the 700 cm −1 region gave new anharmonic constants and values of T rot (79 ± 15 K) and T vib (/2~160 K) which indicate a disequilibrium between the rotational and vibrational degrees of freedom. A band contour analysis of the 3050 cm −1 Fermi triad is used to obtain new values of the Coriolis coupling constants and band origins.

Raman study of CF4 in liquid Ar

The rotational behaviour of CF4 dissolved in liquid argon is derived from the band contour analysis of Raman spectra recorded over the concentration range from 10-2 mole fraction to 1 mole fraction at 85 K. The angular momentum correlation times have been determined with the help of the J-diffusion model and used to apply the rough hard sphere model. A study of the transition dipole-transition dipole (TD-TD) interaction is made using the v 3 mode at 85 K for different concentrations.

The millimeter-wave spectrum of CF 3Cl

The rotational spectra of CF 3 35Cl and CF 3 37Cl in their ground vibrational states were recorded in the microwave and millimeter-wave region, and analyzed to give precise values of the B rotational constants, centrifugal distortion constants, and quadrupole coupling constants. In addition, rotational spectra for the doubly degenerate states v 5 = 1 and v 6 = 1 of CF 3 35Cl were analyzed to yield values of ζ 5 and ζ 6. These are in good agreement with those obtained from Raman and infrared band contour analysis.

Millimetre-wave spectrum of CF3Br

The millimetre-wave rotational spectra of CF379Br and CF381Br have been measured in the ground and low-lying excited states. Analysis of the ground-state spectra has yielded precise values of the rotational and centrifugal distortion constants, as well as bromine nuclear quadrupole coupling constants. For the doubly degenerate states the Coriolis coupling constants ζ5 and ζ6 have also been determined; the values are in good agreement with those obtained from infrared and Raman band contour analysis.

ChemInform Abstract: CONFORMATION AND VIBRATIONAL SPECTRA OF 1,5‐HEXADIYNE (BIPROPARGYL) AND 1,5‐HEXADIYNE‐1,6‐D2

Abstract The infrared spectra of 1,5-hexadiyne (bipropargyl) and 1,5-hexadiyne-1,6- d 2 as vapours, liquids, as solutes in various solvents and as crystalline solids at low temperatures and at high pressures have been recorded. Raman spectra were obtained for the liquids, including semiquantitative polarization measurements, and for the low temperature crystals. The data were interpreted in terms of two conformers, anti and gauche , in the vapour and liquid state and one, the anti, in the crystalline forms. A phase transition for 1,5-hexadiyne was observed at ca. 240 K. Both the high and low temperature crystals had molecules in the anti conformer. Interpretation of the spectra in terms of conformational equilibria was facilitated by a thorough vapour phase band contour analysis. With a few exceptions, all the vibrational fundamentals for both conformers were assigned and found to be in good agreement with results from normal coordinate calculations.

Conformation and vibrational spectra of 1,5-hexadiyne (bipropargyl) and 1,5-hexadiyne-1,6- d2

The infrared spectra of 1,5-hexadiyne (bipropargyl) and 1,5-hexadiyne-1,6- d 2 as vapours, liquids, as solutes in various solvents and as crystalline solids at low temperatures and at high pressures have been recorded. Raman spectra were obtained for the liquids, including semiquantitative polarization measurements, and for the low temperature crystals. The data were interpreted in terms of two conformers, anti and gauche, in the vapour and liquid state and one, the anti, in the crystalline forms. A phase transition for 1,5-hexadiyne was observed at ca. 240 K. Both the high and low temperature crystals had molecules in the anti conformer. Interpretation of the spectra in terms of conformational equilibria was facilitated by a thorough vapour phase band contour analysis. With a few exceptions, all the vibrational fundamentals for both conformers were assigned and found to be in good agreement with results from normal coordinate calculations.

IR band contour analysis in the benzene-nitrobenzene system

Contours of the 1037 cm −1 band of benzene and the 935 cm −1 band of nitrobenzene in the benzene-nitrobenzene system have been analysed. Correlation times of benzene and nitrobenzene are independent of concentration. The correlation time of benzene describes motion about the C 6 axis. Vibrational relaxation is a dominant broadening factor for nitrobenzene.

A study of the absolute infrared intensity of ν3, absorption from vibrationally excited molecules, and the vapor pressure of UF6

Results are presented from laser diode studies of ν3 transition of UF6 in the 16 μm region using a very long optical path absorption cell. The ν3 Q-branch and several individual rotational transitions have been recorded in the temperature range between 165 and 295 K. From the ν3 band contour analysis and the line intensity measurements, the vibrational band strength of the ν3 transition, S0V=710±120 km mole−1, was obtained. From absorption measurements of a UF6 sample in the cooled cell at pressures from 10−3 to 10−5 Torr, the vapor pressure curve of UF6 was extended to the temperature range down to 165 K. A new technique is described allowing us to obtain diode laser ’’survey’’ spectra over a range of 25 cm−1 by ’’mode scans.’’ This technique allows us to measure the changes in the band shape of ν3 as a function of temperature, and thus learn something about ’’hot band’’ absorption from vibrationally excited molecules.

Molecular motions in liquid NOF3

The rotational behaviour of NOF3 is derived from the band contour analysis of the Raman spectra recorded over the liquid phase. The angular momentum correlation times derived from the J diffusion model show us that this C 3v molecule rotates almost isotropically. The band profiles are interpreted in terms of the rough hard sphere model.

Matrix isolation studies (i.r., Raman), band contour analysis and molecular force field of OPCl 3

The i.r. and Raman spectra of matrix-isolated OPCl 3 have been measured to determine the 35Cl 37Cl vibrational isotope shifts. A band contour analysis of the E-block fundamentals, ν 4 and ν 5, has been carried out for the OPCl 3 vapour to obtain the Coriolis coupling constants. Force constants have been determined from the vibrational frequencies, isotope shifts, Coriolis coupling constants and centrifugal distortion constants. The anharmonicity constant X 16 has also been determined.

ChemInform Abstract: INFRARED BAND CONTOUR ANALYSIS AND MOLECULAR CONSTANTS OF THIOPHOSPHORYL FLUORIDE AND NITROGEN SULFIDE FLUORIDE (NSF3)

Chemischer InformationsdienstVolume 10, Issue 40 Physical Inorganic Chemistry ChemInform Abstract: INFRARED BAND CONTOUR ANALYSIS AND MOLECULAR CONSTANTS OF THIOPHOSPHORYL FLUORIDE AND NITROGEN SULFIDE FLUORIDE (NSF3) F. KOENIGER, F. KOENIGERSearch for more papers by this authorC. E. BLOM, C. E. BLOMSearch for more papers by this authorA. MUELLER, A. MUELLERSearch for more papers by this author F. KOENIGER, F. KOENIGERSearch for more papers by this authorC. E. BLOM, C. E. BLOMSearch for more papers by this authorA. MUELLER, A. MUELLERSearch for more papers by this author First published: October 2, 1979 https://doi.org/10.1002/chin.197940005AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue40October 2, 1979 RelatedInformation

Infrared band contour analysis and molecular constants of SPF3 and NSF3

Infrared spectra of gaseous SPF 3 and NSF 3 have been recorded at various temperatures. The band contours of the E fundamentals were analyzed by computer simulation taking into account the dependence of the rotational constants on the vibrational state. The ζ values together with centrifugal distortion constants (only for SPF 3 ) and isotope shifts Δν i ( 32 S/ 34 S) were used as additional data in force constant calculations. CNDO calculations have been carried out to distinguish between two sets of force constants for the E block of NSF 3 . An interpretation of the calculated stretch-stretch interaction force constants, f rR , is given. Anharmonicity constants X 46 for SPF 3 and NSF 3 were determined.

Quadratic potential functions for the boron trihalides

General quadratic compliance constants have been evaluated for the boron trihalides using frequency data and Coriolis coupling constants obtained from a variety of sources. Coriolis data from band contour analysis are too imprecise to help determine the E′ symmetry potential constants. Solutions obtained using Cyvin's Coriolis constants appear to be reasonable on the basis of trends in the valence compliants and interaction displacement coordinates. The semiempirical SCF-MO scheme MNDO has been employed to establish prior constraints of the interaction displacement coordinates in the estimate of the quadratic potential constants for BF 3 and BCl 3.

ChemInform Abstract: ROTATIONAL ANALYSIS OF THE 1B2U(ΠΠ*) ← 1A1G(610) BAND OF BENZENE AND HELIUM‐BENZENE VAN DER WAALS COMPLEXES IN A SUPERSONIC JET

The fluorescence excitation spectrum of benzene at a rotational temperature of 0.3 K has been observed using both pulsed and continuously operated supersonic free jets. Individual lines of the 1B2u(ππ) ←1A1g, (610) band at 259 nm have been clearly resolved and analyzed. Rotational and Coriolis constants as derived from these resolved spectra are in agreement with those derived from previous band contour analyses of room temperature spectra. Rotational analyses of the corresponding spectral band for the He–benzene and He2–benzene van der Waals complexes are also reported. In both complexes the helium atoms are found to lie on the C6 symmetry axis approximately 3.5 A above (and/or below) the plane of the benzene ring. Sufficient rotational cooling is achieved in these supersonic expansions so that ≳95% of all benzene molecules are relaxed to the lowest rotational state available (consistent with nonrelaxation of nuclear spins).

Rotational analysis of the 1B2u(ππ) ←1A1g, (61) band of benzene and helium–benzene van der Waals complexes in a supersonic jet

The fluorescence excitation spectrum of benzene at a rotational temperature of 0.3 K has been observed using both pulsed and continuously operated supersonic free jets. Individual lines of the 1B2u(ππ) ←1A1g, (610) band at 259 nm have been clearly resolved and analyzed. Rotational and Coriolis constants as derived from these resolved spectra are in agreement with those derived from previous band contour analyses of room temperature spectra. Rotational analyses of the corresponding spectral band for the He–benzene and He2–benzene van der Waals complexes are also reported. In both complexes the helium atoms are found to lie on the C6 symmetry axis approximately 3.5 Å above (and/or below) the plane of the benzene ring. Sufficient rotational cooling is achieved in these supersonic expansions so that ≳95% of all benzene molecules are relaxed to the lowest rotational state available (consistent with nonrelaxation of nuclear spins).

Infrared Spectroscopy in Supersonic Molecular Beams: ν3 Band of SF6 at 10.6 µm

A band contour analysis is shown for the ν3 absorption of the flow-cooled SF6. Temperature dependence of the absorption feature is simulated. The possible utility of this technique as a temperature probe of flow-cooled gas mixtures is discussed.

Infrared Intensity Measurements by Band Contour Analysis

A spectroscopic band profile that can be used for asymmetric as well as for symmetric bands is proposed. The meaning of the asymmetry parameter is discussed, and the applications of this profile in infrared intensity determinations are examined.

Matrix isolation studies and force constant calculations on SPF 3 and NSF 3

The i.r. spectra of matrix isolated SPF 3, ★SPF 3 (enriched with 34S isotopes) and NSF 3 have been measured for the determination of 32S/ 34S isotope shifts. A band contour analysis of the E block fundamentals has been carried out for gaseous SPF 3 and NSF 3 at different temperatures to obtain ζ constants. Force constants have been calculated using all known additional data and on the basis of PED calculations band assignments are given. An interpretation of the calculated values for the stretch-stretch-interaction force constants f rR has been given.

The 271-nm electronic spectrum of indane (benzocyclopentene): Rotational band contour analysis and investigation of puckering in the five-membered ring

Rotational contour analysis of the 0 0 0 band of the 271-nm system of indane shows that it is principally type A and therefore that the transition moment is polarized along very nearly the same direction as the corresponding transition in o-difluorobenzene, where it is polarized along the C 2-axis. Using the C 3 point group the electronic assignment in indane is A ̃ 1A′- X ̃ 1A′ but using the C 2 v point group, to which the molecule approximates as far as its π-electron structure is concerned, the assignment is A ̃ 1A 1- X ̃ 1A 1 . Sequence bands in ν 35, the puckering vibration of the CH 2 group in the 2-position in the five-membered ring, show splitting into closely spaced pairs which increases with v. The observations imply a W-shaped potential function for ν 35 in the ground electronic state with tunneling through the barrier producing splitting of vibrational levels. The splitting in the pairs of sequence bands, observed up to the 35 6 6, 35 7 staggered7 pair, reflect small changes of splittings of pairs of levels from the ground to the excited electronic state. There is no evidence to indicate whether this is due to a small increase or decrease of the barrier height. Although the ground-state potential function for ν 35 is not known the results from the electronic spectrum indicate that the barrier is much higher than for the corresponding vibration of cyclopentene, for which it is 232 cm −1. Observations in the corresponding band system of 2-dideuteroindane are consistent with the interpretation of bands involving ν 35.