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The KnowledgeBank at OSU (76.105 recursos)

Knowledge Bank contains collections of presentations, publications and reports related to Ohio State University.

Abstracts of OSU International Symposium on Molecular Spectroscopy 1980-1989

Mostrando recursos 1 - 20 de 2.971

  1. THE ROTATIONAL RKR METHOD

    Nesbitt, David J.; Child, Mark S.
    In the rapidly growing field of high resolution infrared spectroscopy of van der Waals complexes, one often obtains a wealth of rotational information for a single vibrational state. A new RKR based Method is described for extracting one dimensional potentials via inversion of high precision data on rotational energy levels alone. This method proves remarkably successful at quantitatively reproducing intermolecular potentials from rotational data for I) weakly bound (e.g. model van der Waals complexes) and ii) strongly bound (e.g. $v-O$ rotational levels of $H_{2} X^{1}\Sigma_{g})$ molecules.

  2. LASER-INDUCED FLUORESCENCE STUDIES OF THE A-X AND B-X SYSTEMS OF THE NCO RADICAL

    Sullivan, Brian J.; Smith, Gregory P.; Crosley, David R.
    NCO was produced in a low-pressure flow system by reacting HNCO with F atoms generated in a discharge in $CF_{4}/He$. Utilizing a Nd:YAG-pumped dye laser, excitation spectra of the $A^{2}\Sigma^{+}-X^{2}\Pi_{1}$ system and the $B^{2}\Pi_{1}-X^{2}\Pi_{1}$ system were obtained between $4400-3980 \AA$ and $3156-3142 \AA$ respectively. Signals were read out using a boxear intergrator, which was operated in a scanning mode for lifetime runs. A small monochromator, capable of $1 \AA$ resolution, was used to obtain fluorescence spectra. Five vibrational levels (0,0,0; 0,1,0; 1,0,0; 0,2,0; 0,0,1) of the A state were probed, and assignments could be made following Dixon (1). The radiative...

  3. LASER INDUCED FLUORESCENCE FROM DISSOCIATIVE AND PREDISSOCIATIVE STATES OF OZONE

    Imry, D.; Katayama, D. H.; Kinsey, J. L.; Field, R. W.
    Laser induced fluorescent (LIF) from bound states of molecules is well known but LIF from dissociative states such as the upper electronic state of the Huggins bands and Hartley continuum of ozone has not been reported previously. Recently, we used the fourth harmonic of a Nd:YAG laser at 266 nm to excite the Hartley continuum and observed the dispersed fluorescence which clearly showed vibrational structure for the ground state of ozone. We have also obtained the excitation spectrum for a number of Huggins bands by using a tunable dye laser pumped by the Nd:YAG laser. We will discuss the ozone...

  4. PHOTODISSOCIATION OF OZONE AT 248 nm

    Wine, P. H.; Ravishankara, A. R.
    Excitation of $O_{3}$ in the strong Hartley absorption band centered at 255 nm results in dissociation via two energetically and spin allowed channels: [FIGURE]. The branching ratio for production of ground state and electronically excited oxygen atoms is required for understanding ozone spectroscopy and photochemistry, and is a critical parameter in models of atmospheric chemistry. We have monitored $O(^{3}P_{J})$ using time resolved resonance fluorescence detection following 248 nm laser photolysis of $O_{3}/He$ and $O_{3}/He/R$ mixtures $(R = N_{2}, CH_{4})$. From these data, the fraction of photodissociation events leading to the production of $O(^{3}P_{J})$, i.e., $\Phi [O(^{3}P_{j})]/\Phi[O(^{1}D_{2})]$. has been determined to...

  5. LASER MAGNETIC RESONANCE SPECTRUM OF THE $\nu _{2}$ BAND OF $AsH_{2}^{\ast}$

    Muenchausen, R. E.; McCoy, W. J.; Hills, G. W.
    The $\nu_{2}$ bending mode of the $AsH_{2}$ radical in the $\tilde{X}^{2}B_{1}$ state has been investigated using $CO_{2}$ laser magnetic resonance spectroscopy. A large number of resonances have been observed in the $920-1070 cm^{-1}$ region. Many resonances show the characteristic quarters of resolved $^{75}As (T=3/2)$ hyperline structure. The $AsH_{2}$ radical was produced in a discharge flow system by adding to arsine $(AsH_{3})$ the products of a microwave discharge of $H_{2}$ in Ar. The current evidence for the active species as $AsH_{2}$ is mainly chemical. The results of the spectrum assignment and parameter determination, currently underway, should confirm the identity.

  6. MICROWAVE STUDIES OF $\tilde{A}$, NHD AND $\tilde{X}, ND_{2}$ USING MICROWAVE OPTICAL DOUBLE RESONANCE

    Brown, J. M.; Cook, J. M.; Hills, G. W.
    Microwave optical double resonance spectroscopy has been used to study microwave transitions in the 1.5 CHz-12.4 CHz spectral region for both NHD and $ND_{2}$. The studies of NHD have focussed on determining magnetic hyperfine coupling constants for $^{14}N$ and $^{1}H (^{2}D)$ in the $\Pi(0, 10, 0)$ and (0, 10, 0) vibration states of the $\tilde{A} {^{2}A^{1}}$ state. Over 100 hyperfine components involving 11 magnetic dipole transitions of the type, $^{N}K_{a}K_{C}, J-N-1_{2} \leftrightarrow J-N + 1_{2}$, and one electric dipole transition. $2_{20}, F_{1} \leftrightarrow 2_{21}$. $F_{2}\Delta (0, 11, 0)$, have been observed. For $ND_{2}$, over 200 microwave transitions, all of the...

  7. MICROWAVE OPTICAL DOUBLE RESONANCE SPECTROSCOPY USED AS AN ASSIGNMENT METHOD IN OPTICAL $SPECTROSCOPY^{\ast}$

    Hills, G. W.
    In microwave optical double resonance spectroscopy (MODR) the primary interest is generally in the accurate measurement of the microwave adsorption frequencies. In the work described here though, known microwave transitional frequencies are pumped and the optical transitions frequency of the dye laser is swept. MODR signals are seen in both 3-level and 4-level (collisional) schemes. The method has been applied to $NH_{2}$ on the $1_{10}, J-1/2, \Pi(0, 10, 0) \leftrightarrow u$ transition around $6.3 CHz^{1}$. Double resonance signals were observed for many known ortho levels in $\Pi(0, 10, 0) (N < 7), \Phi(0, 10, 0), \Phi (1, 6, 0)$ etc....

  8. STIMULATED EMISSION PUMPING OF HIGHLY EXCITED VIBRATIONAL LEVELS OF $\tilde{\chi} ^{1}A_{1} H_{2}CO$

    Reisner, D. E.; Dai, H. L.; Vaccaro, P. H.; Kittrell, C.; Kinsey, J. L.; Field, R. W.
    Stimulated Emission Pumping (SEP), a double resonance technique, has been developed as a means to probe highly excited vibrational levels of ground electronic states of polyatomic molecules, We report initial experiments on $H_{2}CO$ in a static cell. A PUMP laser populates a known level $(4^{1}_{0} transition)$ or the $\tilde{A} {^{1}A_{2}}$ state. A subsequent DUMP laser stimulates emission downward to vibrational levels of the $\tilde{\chi} {^{1}A_{1}}$ state. Combination levels in both the out-of-plane bend $(v_{4}=4)$ and the C-O stretch $(v_{2}=3)$ have been reached via the $4^{1}_{4}$ and $2^{0}_{3}4^{1}_{0}$ transitions respectively.

  9. ANALYSIS OF THE 5800 \AA SCHUSTER BAND OF THE $ND_{4}$ RADICAL

    Herzberg, G.; Hougen, Jon T.
    An emission system first observed over a hundred years ago by Schuster in various DC discharges in flowing $NH_{3}$ has been restudied at the NRC in Ottawa, where mixed isotopic spectra using both D and $^{15}N$ allowed the carrier of the spectrum to be positively $identified^{1}$ as $NH_{4}$. The results of ab initio $calculations^{2}$ and a preliminary rotational $analysis^{1}$ led to a provisional assignment of one hand as a $(3d)^{2}F_{2} - (3s)^{2}A_{1}$ Rydberg transition, even though such a transition would be parity forbidden in the united atom limit. The present work attempts to place the original rotational analysis on a...

  10. BANDS OF THE 2400 \AA SYSTEM OF ACETYLENE.

    Watson, J. K. G.; Herman, M.; Van Craen, J. C.; Colin, R.
    Detailed assignments of the longer wavelength bands of the $2400 \AA$ absorption system $A^{-1}A_{\mu}(C_{2h})-\tilde{X}^{1}\Sigma^{+}_{g}(D_{\omega h})$ of acetylens $(C_{2}H_{2})$ have been performed, including revisions of some subband assignments. The wavenumbers of the lines of the stronger bands have been fitted simultaneously employing a linear molecule Hamiltonian for the lower electronic state, with inclusion of $\ell$-doubling and $\ell$-resonance effecta in the lavels of the $\pi_{g}$ vibration $\upsilon_{4}$ for $\upsilon_{\Delta} \epsilon 4$, and an asymmetric top Hamiltonian with centrifugal distortion for the upper electronic state. The relative intensities of different subbands, including the effects of axis-switching, will be discussed. The observed vibrational levels...

  11. EMISSION SPECTRUM OF TRITIATED ACETYLENE

    Schmieder, R. W.
    The spectrum of visible emission from tritiated acetylene gas in closed cell with no external excitation has been recorded. Two forms of gas were used: (1) $C_{2}HT$, synthesized by a modified Wilzbach process and mixed with $C_{2}H_{2}$: (2) mixtures of $C_{2}H_{2}$ and $T_{2}$. The gases were held in stainless steel cells of about $20 cm^{3}$ volume with sapphire windows. Pressures were 100-300 Torr. Emitted photons were analyzed with a 1/2-m monochromator, an RCA 31034A-12 photomultiplier, and standard counting electronics. The spectra exhibit the well-known Swan bands of $C_{2}$ and a broad band which may be $C_{2}H$. The CH 431.5 nm...

  12. HIGH RESOLUTION OBSERVATIONS OF LASER EXCITED FLUORESCENCE IN $NO_{2}$

    Hardwick, J. H.
    Fluorescence of nitrogen dioxide excited by several lines of an argon ion laser has been dispersed and recorded with a resolution of $0.05 cm^{-1}$. The fluorescence wavelengths thus observed allow precise vibrational and rotational constants to be determined for high-lying vibrational states of $NO_{2}$. The ``continuum'' fluorescence reported by previous workers exhibits no identifiable structure even at high resolution.

  13. DIPOLE MOMENTS OF VIBRATIONALLY EXCITED FORMALDEHYDE

    Dai, H. L.; Vaccaro, P. H.; Field, R. W.; Kinsey, J. L.
    Dipole moments for highly excited virbrational levels of formaldehyde in the $\tilde{\chi} {}^1{A}_{1}$ ground electronic state have been measured by utilizing the recently developed technique of Stimulated Emission Pumping (SEP) in conjunction with the Stark effect. Moments for the overtone and combination bands of the $\nu_{2}$ and $\nu_{4}$ vibrational modes are measured with better than 1% precision.

  14. MICROWAVE SPECTRUM AND CONFORMATION OF CIS-1, 2-DIFLUOROETHYLENE OZONIDE (FCHOOFCHO)

    Hillig, K. W., II; Kuczkowski, R. L.
    The microwave spectrum of cis-difluoroethylene ozonide (cis-3, 5-difluoro-1, 2, 4-trioxolane) has been investigated by RF-microwave double resonance in the region of 26.5 - 40.0 GHz. The spectrum consists of two interwoven sets of transitions of similar intensity, arising from two vibrational states of the molecule. The predominant features of the DR spectra are several series of $\mu_{b}$ Q-branch pairs (pumped by $\mu_{c} RF$ transitions), with very few R-branch lines seen. The rotational constants of one state are A = 4256.9, B = 2923.7, and C = 2347.4, giving (A-C) = 1909.5 and k = -D.396. For the other state only...

  15. MICROWAVE SPECTRUM AND STRUCTURE OF 1,2,4-TRITHIOLANE (HCHSSHCHS)

    Borseth, D. G.; Kuczkowski, R. L.
    The microwave spectrum of 1,2,4-trithiolane has been examined in the region 18.0 - 40.0 GHz. The spectrum consisted of A-dipole transitions which exhibited nuclear spin statistics (10:6) conforming to $C_{2}$ symmetry, similar to the analogous ethylene ozonide (1,2,4-trioxolane). The ground state rotational constants were determined to be 3819.37, 2621.11 and 1710.60 MHz. The dipole moment is $\mu_{t} = \mu_{a} = 0.47D$. 3,5-dideuterio-1,2,4-trithiolane has been prepared and all three possible species' microwave spectra have been assigned.

  16. OZONOLYSIS OF CIS- AND TRANS-1,2-DIFLUOROETHYLENE: MICROWAVE SPECTRUM OF CIS, TRANS-1,2,3-TRIFLUOROCYCLOPROPANE

    Agopovich, J.; Gillies, C. W.
    The microwave spectrum of cis, trans-1,2,3-trifluorocyclopropane, $CHFCHFCFH^{1}$, was investigated in the region of 26.5 = 40.0 GHz, From the assignment of $\mu_{a}$ and $\mu_{e}$ type R-branch transitions the following rotational constants (MHz) were obtained for the ground vibrational state: $A=4755,000 \pm 0.005, B=3145,729 \pm 0.002$ and $C = 2114.071 \pm 0.002$. The electric dipole moment was measured to be $\mu_{a} = 1.146 \pm 0.015$ Debye, $\mu_{c} =1.818 \pm .032$ Debye and $\mu_{T} = 2.149 \pm .035$ Debye. In addition, microwave transitions were assigned for a vibrationally excited state. Five deuterated isotopes of CHFCHFCFH were synthesized by the reaction of ozone...

  17. THE MICROWAVE SPECTRUM OF S-CIS AND S-TRANS ACROLEIN

    Blom, C. E.; Bauder, A.
    The microwave spectrum of the second conformer of acrolein has been assigned. Rotational constants A=22831.650 (16) MHz, B=6241.047 (3) MHz and C=4902.206 (3) MHz of s-cis acrolein in the vibrational ground states were determined from 42 transitions between 8 and 60 Ghz. The small value of the inertia defect establishes the planarity of the molecule. Rotational transitions in excited states of s-cis and s-trans acrolein have been analyzeed. The shifts of the rotational constants upon vibrational excitation have been interpreted on the basis of a flexible model for torsional motions and vibrational interactions.

  18. MICROWAVE SPECTRA AND STRUCTURE OF METHYLGERMYL BROMIDE

    Durig, J. R.; Mohamad, A. B.; Li, Y. S.
    The microwave spectra of ${CH_{3}}^{70}{GeH_{2}}^{70}Br, {CH_{3}}^{70}{GeH^{81}}Br, {CH_{3}}^{72}{GeH_{2}}^{79}Br, {CH_{3}}{GeH_{2}}^{81}Br, {CH_{3}}^{74}{GeH_{2}}^{79}Br$, and ${CH_{3}}^{74}{GeH_{2}}^{81}Br$ have been recorded from 18.0 to 39.0 GHz. Only a-type transitions were observed and R-branch assignments have been made for the ground vibrational state. From a diagnostic least-squares adjustment to fit the rotational constants, the $r_{0}$ structural parameters have been obtained. These results will be compared to the corresponding quantities in some similar molecules.

  19. MICROWAVE TORSIONAL-ROTATIONAL SPECTRA OF $CH_{2}DSH$ AND $CHD_{2}SH^{\ast}$

    Su, C. F.; Quade, C. R.
    The torsional-rotational spectra of $CH_{2}DSH$ and $CHD_{2}SH$ have been studied from 12.4 to 50.0 GHz. For the symmetric (trans) configuration, rigid rotor n- and b-dipole transitions have been assigned. For the two asymmetric (gauche) configurations a-, b- and c-dipole lines have been assigned. In this case, the a-dipole lines show a small doubling and are nearly rigid rotor; the b-dipole lines have a large doubling due to internal angular momentum mixing the two asymmetric states and the second order contribution to the rotational coefficient A from the internal angular momentum; and the c-dipole lines are doubled to an even greater...

  20. R-BRANCH MICROWAVE SPECTRUM OF METHYLAMINE

    Lees, R. M.; Malghani, M. S.; Mukhopadhyay, Indranath; McGhee, P.; Johnson, Donald R.; Lovas, F. J.
    The a-type R-branch $J=1 \leftarrow 0$ and $J = 2\leftarrow 1$ multiplets of $CH_{3}NH_{2}$ have been investigated at 44 GHz and 88 GHz, respectively, in order to provide laboratory data for radio astronomy and to permit determination of certain of the a-type molecular constants. Identification of all torsion- inversion components of the $J= 2 \leftarrow 1$ multiplet has been made for the ground torsional state, and partial identification for the first and second excited torsional states, Further progress has also been made on the assignment of the $J = 1 \leftarrow 0$ $multiplet^{1}$, and on the resolution of some ambiguities...

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