• 제목/요약/키워드: Vibrational Mode

검색결과 213건 처리시간 0.025초

외팔보의 동적응답과 진동모드 분석 (An Analysis of the Dynamic Response and Vibrational Mode for the Cantilevered Beam)

  • 김예현;고영준;강병용;장호경
    • 한국음향학회지
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    • 제16권1호
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    • pp.16-23
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    • 1997
  • 강제진동에 의한 외팔보의 동적응답과 진동모드를 연구하였다. Bernoulli-Euler 이론과 유한요소법을 이용하여 외팔보의 고유진동수와 진동모드를 수치해석하고 실험으로 측정하여 비교하였다. 가진주파수를 1Hz에서 70Hz까지 변화시켜 외팔보의 1차, 2차 공진주파수를 구하고, 응답위치에 따른 진동 변위를 측정하여 진동모드를 살펴보았다. 실험결과에서 외팔보의 절점(node)이 1차모드에서는 0.2차모드에서는 0,0.786으로 측정되었다. 외팔보의 공진주파수와 진동모드에 대해 이론적으로 예상했던 결과와 실험으로 측정한 결과가 거의 일치하였다.

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Rovibrational Nonequilibrium of Nitrogen Behind a Strong Normal Shock Wave

  • Kim, Jae Gang
    • International Journal of Aeronautical and Space Sciences
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    • 제18권1호
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    • pp.28-37
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    • 2017
  • Recent modeling of thermal nonequilibrium processes in simple molecules like hydrogen and nitrogen has indicated that rotational nonequilibrium becomes as important as vibrational nonequilibrium at high temperatures. In the present work, in order to analyze rovibrational nonequilibrium, the rotational mode is separated from the translational-rotational mode that is usually considered as an equilibrium mode in two- and multi-temperature models. Then, the translational, rotational, and electron-electronic-vibrational modes are considered separately in describing the thermochemical nonequilibrium of nitrogen behind a strong normal shock wave. The energy transfer for each energy mode is described by recently evaluated relaxation time parameters including the rotational-to-vibrational energy transfer. One-dimensional post-normal shock flow equations are constructed with these thermochemical models, and post-normal shock flow calculations are performed for the conditions of existing shock-tube experiments. In comparisons with the experimental measurements, it is shown that the present thermochemical model is able to describe the rotational and electron-electronic-vibrational relaxation processes of nitrogen behind a strong shock wave.

Vibrational Relaxation of Cyanate or Thiocyanate Bound to Ferric Heme Proteins Studied by Femtosecond Infrared Spectroscopy

  • Park, Seongchul;Park, Jaeheung;Lin, Han-Wei;Lim, Manho
    • Bulletin of the Korean Chemical Society
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    • 제35권3호
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    • pp.758-764
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    • 2014
  • Femtosecond vibrational spectroscopy was used to measure the vibrational population relaxation time ($T_1$) of different anions bound to ferric myoglobin ($Mb^{III}$) and hemoglobin ($Hb_{III}$) in $D_2O$ at 293 K. The $T_1$ values of the anti-symmetric stretching (${\nu}_1$) mode of NCS in the $NCS^-$ bound to $Mb^{III}$ ($Mb^{III}$NCS) and $Hb_{III}$ ($Hb_{III}$NCS) in $D_2O$ are $7.2{\pm}0.2$ and $6.6{\pm}0.2$ ps, respectively, which are smaller than that of free NCS. in $D_2O$ (18.3 ps). The $T_1$ values of the ${\nu}_1$ mode of NCO in the $NCO^-$ bound to $Mb^{III}$ ($Mb^{III}$NCO) and $Hb_{III}$ ($Hb_{III}$NCO) in $D_2O$ are $2.4{\pm}0.2$ and $2.6{\pm}0.2$ ps, respectively, which are larger than that of free $NCO^-$ in $D_2O$ ($1.9{\pm}0.2$ ps). The smaller $T_1$ values of the ${\nu}_1$ mode of the heme-bound NCS suggest that intramolecular vibrational relaxation (VR) is the dominant relaxation pathway for the excess vibrational energy. On the other hand, the longer $T_1$ values of the ${\nu}_1$ mode of the heme-bound NCO suggest that intermolecular VR is the dominant relaxation pathway for the excess vibrational energy in the ${\nu}_1$ mode of $NCO^-$ in $D_2O$, and that intramolecular VR becomes more important in the vibrational energy dissipation of the ${\nu}_1$ mode of NCO in $Mb^{III}$NCO and $Hb_{III}$NCO.

Vibration-Rotation Coupling in a Quasilinear Symmetric Triatomic Molecule

  • Lee, Jae-Shin
    • Bulletin of the Korean Chemical Society
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    • 제15권3호
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    • pp.228-236
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    • 1994
  • The effect of the vibration mode coupling induced by the vibration-rotation interaction on total energy was investigated for the states with zero total angular momentum(J=0) in a quasilinear symmetric triatomic molecule of $AB_2$ type using a model potential function with a slight potential barrier to linearity. It is found that the coupling energy becomes larger for the levels of bend and asymmetric stretch modes and smaller for symmetric stretch mode as the excitation of the vibrational modes occurs. The results for the real molecule of $CH_2^+$, which is quasilinear, generally agree with the results for the model potential function in that common mode selective dependence of coupling energy is exhibited in both cases. The differences between the results for the model and real potential function in H-C-H system are analyzed and explained in terms of heavy mixing of the symmetric stretch and bend mode in excited vibrational states of the real molecule of $CH_2^+$. It is shown that the vibrational mode coupling in the potential energy function is primarily responsible for the broken nodal structure and chaotic behavior in highly excited levels of $CH_2^+$ for J= 0.

Vibrational Structure and Predissociation of Ar-CO2 by CO2 Symmetric Stretching Mode Coupled with Ar Motion

  • Jung, Jae-Hoon;Sun, Ho-Sung
    • Bulletin of the Korean Chemical Society
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    • 제23권2호
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    • pp.245-252
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    • 2002
  • The computationally simple quantum mechanical method (VSCF-DWB-IOS) has been applied to studying the Ar-$CO_2$ vibrational predissociation phenomenon. The new methodology utilizes the vibrational self-consistent field method to determine the vibrational structure of the van der Waals complex, the distorted-wave Born approximation for dissociating process, and the infinite-order sudden approximation for the continuum dissociating product of $CO_2$. The dissociation due to the coupling of the symmetric stretching vibrational motion of $CO_2$ with the motion of the Ar van der Waals mode has been extensively investigated. The lifetimes of transient excited vibrational states, linewidths of absorption peak, and the rotational state distributions of the product, $CO_2$ have been computed. It has been found that the lifetime of the Ar-$CO_2$ in excited vibrational state is very long compared with that of triatomic van der Waals complexes and the product $CO_2$ carries a major portion of dissociation energy as a rotational energy.

Picosecond Dynamics of CN--Ligated Ferric Cytochrome c after Photoexcitation Using Time-resolved Vibrational Spectroscopy

  • Kim, Joo-Young;Park, Jae-Heung;Chowdhury, Salina A.;Lim, Man-Ho
    • Bulletin of the Korean Chemical Society
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    • 제31권12호
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    • pp.3771-3776
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    • 2010
  • The dynamics of the $CN^-$-ligated ferric cytochrome c (CytcCN) in $D_2O$ at 283 K following Q-band photoexcitation at 575 nm was observed using femtosecond time-resolved vibrational spectroscopy. The equilibrium vibrational spectrum of the CN stretching mode of CytcCN shows two overlapping bands: one main band (82%) at $2122\;cm^{-1}$ with $23\;cm^{-1}$ full width at half maximum (fwhm) and the other band (18%) at $2116\;cm^{-1}$ with $7\;cm^{-1}$ fwhm. The time-resolved spectra show bleaching of the CN fundamental mode of CytcCN and two absorption features at lower energies. The bleach signal and both absorption features are all formed within the time resolution of the experiment (< 200 fs) and decay with a life time of 1.9 ps. One transient absorption feature, appearing immediately red to the bleach signal, results from the thermal excitation of low-frequency modes of the heme that anharmonically couple to the CN fundamental mode, thereby shifting the CN mode to lower energies. The shift of the CN mode decays with a lifetime of 2 ps, equivalent to the time scale for vibrational cooling of the low-frequency heme modes. The other transient absorption feature, which is 3.3 times weaker than the bleach signal and shifted $27\;cm^{-1}$ toward lower energies, is attributed to the CN mode in an electronically excited state where the CN bond is weakened with a lowered extinction coefficient. These observations suggest that photoexcited CytcCN mainly undergoes ultrafast radiationless relaxation, causing photo-deligation of $CN^-$ from CytcCN highly inefficient. As also observed in $CN^-$-ligated myoglobin, inefficient ligand photodissociation might be a general property of $CN^-$-ligated ferric hemes.

실시간 진동측정시스템에 관한 연구

  • 유재호;반재경;박한규
    • 한국통신학회:학술대회논문집
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    • 한국통신학회 1986년도 춘계학술발표회 논문집
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    • pp.202-205
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    • 1986
  • In this paper, real-time vibration measurement using system is described. Modes getting from different vibrational frequencies of come vibrational plates are rectified and filtered by digitizer and recorded 488 dots(abscissa) printer. PZT and mechanical chopper is placed in front of cw laser for better resolving power. Rayleigh`s mode theory and mode pattern are compared with experimental results.

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CW $CO_{2}$ 레이저의 온도 특성에 관한 해석 (The theoretical analysis of characteristics for temperatures in cw $CO_{2}$ laser)

  • 강동헌;박득일;이주희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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    • pp.465-468
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    • 1988
  • The output power is dependent of the vibrational level temperatures and wall temperature of the discharge tube in cw $CO_{2}$ lasers. The method postulates the introduction of a vibrational temperatures Ti for each vibrational mode. The vibrational and wall temperature are dertermined by the equations of the vibrational energy balance and thermal conductivity.

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Development of Automatic Reactor Internal Vibration Monitoring System Using Fuzzy Peak Detection and Vibration Mode Decision Method

  • Kang, Hyun-Gook;Seong, Poong-Hyun;Park, Heui-Youn;Lee, Cheol-Kwon;Koo, In-Soo
    • Nuclear Engineering and Technology
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    • 제30권1호
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    • pp.8-16
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    • 1998
  • In this work a method to detect the vibrational peak and to decide the vibrational mode of detected peak for core internal vibration monitoring system which is particularly concerned on the core support barrel (CSB) and fuel assemblies is developed. Flow induced vibration and aging process in the reactor internals cause unsoundness of the internal structure. In order to monitor the vibrational status of core internal, signals from the ex-core neutron detectors are transformed into frequency domain. By analyzing transformed frequency domain signal, an analyst can acquire the information on the vibrational characteristics of the structures, i.e., vibration frequencies of each component, vibrational level, modes of vibration, and the causes of the abnormal vibration, if any. This study is focused on the development of the automated monitoring system. Several methods are surveyed to define the peaks in power spectrum and fuzzy theory is used to automatic detection of the vibrational peaks. Fuzzy algorithm is adopted to define the modes of vibration using the peak values from fuzzy peak recognition, phase spectrum, and coherence spectrum.

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Ultrafast Investigation of Vibrational Relaxation and Solvent Coordination Following Photodissociation of Cr$(CO)_6$

  • Seok-Beum Ko;Soo-Chang Yu;J. B. Hopkins
    • Bulletin of the Korean Chemical Society
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    • 제15권9호
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    • pp.762-765
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    • 1994
  • Picosecond time-resolved resonance Raman spectroscopy has been used to study the photochemistry of Cr(CO$)_6$ in cyclohexane following photoexcitation at 266 nm. Photodissociative loss of CO is found to occur within our pulse width of ${\leq}$5 ps by probing the 533 c$m^{-1}$ vibrational mode of ground state Cr(CO$)_6$. The subsequent dynamics after photodissociation are interpreted in terms of solvation, vibrational and electronic relaxations. The vibrational relaxation time of 100 ps and 83 ps are observed by monitoring v=O and v=l of the 381 c$m^{-1}$ transient mode, respectively. No evidence was found for solvation and electronic relaxation occurring on a time scale of ${\leq}$5 ps.