• Title, Summary, Keyword: Vibrational Spectra

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Experimental Determinations of Coherent Multidimensional Vibrational Spectroscopy

  • Besemann, Daniel;Condon, Nicholas;Meyer, Kent;Zhao, Wei;Wright, John C.
    • Bulletin of the Korean Chemical Society
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    • v.24 no.8
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    • pp.1119-1125
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    • 2003
  • Coherent multidimensional vibrational spectroscopy is a new technique for establishing correlations between features in vibrational spectra that are caused by intra- and intermolecular interactions. These interactions cause cross-peaks between vibrational transitions that reflect the coupling. In this paper, we use Doubly Vibrationally Enhanced Infrared Spectroscopy (DOVE-IR) and DOVE-Raman processes to obtain coherent two dimensional vibrational spectra. The spectra are fitted to obtain the dephasing rates and third order susceptibilities $(χ^{(3)})$ for the nonlinear processes. We show that the DOVE $χ^{(3)}$ values are directly related to the molar absorptivities and Raman $χ^{(3)}$. We then use these relationships to obtain estimates for the $χ^{(3)}$ of the stimulated photon echo and $χ^{(5)}$ of the six wave mixing spectroscopies, respectively. We also predict the ratio of the cascaded four wave mixing signal to the six wave mixing signal.

Ab Initio Study of Vibrational Spectra of p-tert-Butylcalix[4]aryl Ester Complexed with Alkali Metal Cation (알칼리금속 양이온과 착물을 형성한 캘릭스[4]아릴에스터의 진동스펙트럼에 대한 순수양자역학적 연구)

  • Choe, Jong-In;Kim, Gwang-Ho
    • Journal of the Korean Chemical Society
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    • v.50 no.1
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    • pp.7-13
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    • 2006
  • infrared(IR) absorption spectra were calculated for the ethyl ester of p-tert-butylcalix[4]arene (1) in the cone conformer and its alkali-metal-ion complex. The vibrational spectra were obtained by restricted Hartree-Fock (RHF) calculations with the 6-31G basis set. The characteristic vibrational frequencies of various C-O and C=O stretching motions of the complexes show that the structure of 1+K+ complex is almost of C4v symmetry compared to 1+Na+ (C2v) analogue. The theoretical results for the host molecule 1 and complex (1+Na+) were compared with the experimental results, and the calculated vibrational frequencies agree well with the features of the experimental spectra.

Comparative Vibrational Spectroscopic Studies Between Nickel, Zinc Tetraphenylporphyrins and Tetraphenylchlorins

  • Song Ok-Keun;Yoon Min-Joong;Chang Jae-Rim;Kim Dongho
    • Bulletin of the Korean Chemical Society
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    • v.10 no.1
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    • pp.39-51
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    • 1989
  • The infrared and resonance Raman spectra are reported for nickel and zinc tetraphenylchlorins. It is found that the IR and RR spectra become more complicated compared with the corresponding porphyrin analogs due to the symmetry changes. Some vibrational parameters like the core size and the symmetry change are examined in accordance with vibrational spectra of other type of chlorins.

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Supersonic Free Jet and Ab initio Studies of Electronic-Vibrational Structures of Fluorene

  • 부봉현;최영식;김택수;강성권;김재룡
    • Bulletin of the Korean Chemical Society
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    • v.16 no.4
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    • pp.341-344
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    • 1995
  • Laser-induced fluorescence (LIF) excitation spectra were measured for fluorene (FR) cooled in pulsed supersonic expansions of He in the range 283.7-296.7 nm. Ab initio studies of FR have also been carried out for determining the electronic and vibrational structures by using the standard 3-21G basis sets. In the LIF excitation spectra of FR, highly resolved vibronic bands are observed having the band origin of 33,791 cm-1. The vibrational bands above the electronic origin were assigned on the basis of the well-characterized electronic vibrational bands reported previously and of normal modes of vibrations derived by our HF/3-21G calculations.

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2,4,6-Triamino-1,3,5-triazin-1-ium Acetate Acetic Acid Solvate Monohydrate. Infrared and Raman Spectra

  • Marchewka, M.K.
    • Bulletin of the Korean Chemical Society
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    • v.25 no.4
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    • pp.466-470
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    • 2004
  • The crystals of the new melaminium salt, i.e. melaminium acetate acetic acid solvate monohydrate, $C_3H_7N_6^+ {\cdot}CH_3COO^- {\cdot}CH_3COOH{\cdot}H_2O$, were obtained by the slow evaporation of an aqueous solution at room temperature. Powder infrared and Raman spectra were measured and interpreted. The vibrational spectra in the region of internal vibrations of ions corroborate structural data recently published by Perpetuo and Janczak.$^1$ Some spectral features of this new crystal are referred to corresponding one for melamine crystal as well as other melamine complexes in crystalline form. Hydrogen-bonded network present in the crystal gives notable vibrational effect.

Density Functional Theory Study of Vibrational Spectra of Anthracene Neutral and Radical Cation

  • 이상연;부봉현
    • Bulletin of the Korean Chemical Society
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    • v.17 no.8
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    • pp.754-759
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    • 1996
  • Ab initio Hartree-Fock and Becke 3-Lee-Yang-Parr (B3LYP) density functional theory calculations using 6-31G* basis set were carried out to study the vibrational spectra of anthracene neutral (h10 and d10) and radical cation (h10). We report results of the fundamental vibrational frequencies obtained on the basis of the calculations. The assignments of fundamentals show a one-to-one correspondence between the observed and calculated fundamentals.

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Electronic and Vibrational Spectroscopy of cis-Diisothiocyanato(1,4,8,11-tetraazacyclotetradecane)chromium(Ⅲ) Thiocyanate

  • Choi, Jong-Ha;Park, Yu-Chul
    • Bulletin of the Korean Chemical Society
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    • v.24 no.3
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    • pp.384-388
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    • 2003
  • The emission and excitation spectra of $cis-[Cr(cyclam)(NCS)_2]NCS$ (cyclam = 1,4,8,11-tetraazacyclotetradecane) taken at 77 K are reported. The infrared and visible spectra at room temperature are also measured. The vibrational intervals due to the electronic ground state are extracted from the far-infrared and emission spectra. The ten pure electronic origins due to spin-allowed and spin-forbidden transitions are assigned by analyzing the absorption and excitation spectra. Using the observed transitions, a ligand field analysis has been performed to determine the bonding properties of the coordinated ligands in the title chromium(Ⅲ) complex. According to the results, it is found that nitrogen atoms of the cyclam ligand have a strong σ-donor character, while the NCS ligand has medium σ- and π-donor properties toward chromium(Ⅲ) ion.

Structure, Modified Scaled Quantum Mechanical Force Field and A Priori Prediction of Vibrational Spectra and Their Assignment and Exponential Scaling of Frequencies of Triphenylene

  • Bandyopadhyay, Indrajit
    • Bulletin of the Korean Chemical Society
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    • v.24 no.6
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    • pp.717-722
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    • 2003
  • The structure, force field and vibrational spectra of triphenylene are studied by $B3LYP/6-31G^*$(5d) level of theory. The results are compared to those of the related system, phenanthrene. The scale factors in nonredundant local coordinates obtained after fitting the DFT frequencies to the experimental numbers of phenanthrene-$d_0 and -d_{10}$ are transferred to predict the spectra and assignment of triphenylene for in-plane modes. The frequencies based on scaling methodology due to Lee et al. are also obtained. These frequencies are compared with the predicted numbers based on scale factors from phenanthrene. Probable assignment for out-of-plane modes is proposed based on simple scaling of Scott and Radom (scale factor 0.9614) as well as by scaling methodology by Lee et al.

Synthesis, Crystal Structure, Spectra Characterization and DFT Studies on a Di-Cycle Pyrazoline Derivative

  • Song, Jie;Zhao, Pu Su;Zhang, Wei Guang
    • Bulletin of the Korean Chemical Society
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    • v.31 no.7
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    • pp.1875-1880
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    • 2010
  • A dicycle pyrazoline derivative, 1-phenyl-5-(p-fluorophenyl)-3,4-($\alpha$-p-fluoro-tolylenecyclohexano) pyrazoline, was synthesized and characterized by elemental analysis, IR, UV-vis, fluorescence spectra and X-ray single crystal diffraction. Density function theory (DFT) calculations were performed by using B3LYP method with 6-$311G^{**}$ basis set. The optimized geometry can well simulate the molecular structure. Vibrational frequencies were predicted, assigned and compared with the experimental values, which suggest that B3LYP/6-$311G^{**}$ method can well predict the IR spectra. Both the experimental electronic absorption spectra and the predicted ones by B3LYP/6-$311G^{**}$ method reveal three electron-transition bands, with the theoretical ones having some red shifts compared with the experimental data. Natural bond orbital analyses indicate that the absorption bands are mainly derived from the contribution of n $\rightarrow\pi^*$ and $\pi\rightarrow\pi^*$ transitions. Fluorescence spectra determination shows that the title compound can emit blue-light at about 478 nm. On the basis of vibrational analysis, the thermodynamic properties of title compound at different temperature have been calculated, revealing the correlations between $C^0_{p,m}$, $S^0_m$, $H^0_m$ and temperature.

Resonantly-enhanced Two-photon Ionization and Mass-Analyzed Threshold Ionization (MATI) Spectroscopy of 2-Hydroxypyridine

  • Lee, Dae-Hyun;Baek, Sun-Jong;Choi, Kyo-Won;Choi, Young-S.;Kim, Sang-Kyu
    • Bulletin of the Korean Chemical Society
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    • v.23 no.2
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    • pp.277-280
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    • 2002
  • Mass-analyzed threshold ionization (MATI) spectra of 2-hydroxypyridines existing as lactims (2-pyridinol) in a molecular beam are obtained via (1+1') two-photon process to give accurate ionization energies of 8.9344${\pm}$0.0005 and 8.9284${\pm}$0.0005 eV for 2-pyridinol (2Py-OH) and its deuterated analogue (2Py-OD), respectively. Resonantly-enhanced two-photon ionization spectra of these compounds are also presented to give vibrational structures of their $S_1$ states. Vibrational frequencies of 2Py-OH and 2Py-OD in ionic ground states are accurately determined from MATI spectra taken via various $S_1$ intermediate states, and associated vibrational modes are assigned with the aid of ab initio calculations.