Sang Kyu Kim
KAIST 물리학과 · 물리·천문학
Sang Kyu Kim 교수의 연구실은 분자의 동적 거동을 초고속 레이저와 고해상도 분광법을 통해 정밀하게 분석하는 데 초점을 맞추고 있습니다. 주로 표면 증강 라만 분광법(SERS)을 활용해 아미노산 및 펩타이드의 표면에서의 정렬과 상호작용을 연구하며, 반응 동역학에서는 고에너지 상태에서의 비통계적 거동, 양자 터널링, C–C 결합 분해의 비공진성 메커니즘을 시간 해상도가 피코초에서 펌토초 수준으로 규명하고 있습니다. 특히, 광분해 반응에서의 제품 분포와 동역학적 경로를 정량적으로 분석함으로써 반응 경로의 다차원성과 전자 구조의 영향을 밝혀내는 데 기여하고 있습니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
Abstract The surface‐enhanced Raman (SER) spectra of aromatic amino acids ( L ‐phenylalanine, L ‐tyrosine and tryptophan) and their glycyl dipeptides (glycyl‐ L ‐phenylalanine, glycyl‐ L ‐tyrosine and glycyl‐ L ‐tryptophan) adsorbed on Ag colloidal particles have been obtained. The surface‐enhanced and ordinary Raman spectra show satisfactory correlations. The most prominent features in the SER spectra of all compounds are the strongly enhanced peaks at about 930 and 1390 cm −1 due to the CCOO
When a reaction involving two equivalent bonds has sufficient energy to break both of them, it can proceed by either a concerted or a stepwise mechanism. For Norrish type-I and other reactions, this issue has been controversial since direct time resolution of the individual C–C cleavage events was not possible. Here, for the elementary α-cleavage of acetone, we report on the femtosecond resolution of the intermediates using mass spectrometry. The results show the nonconcertedness of the reaction
Rate constants for the unimolecular dissociation of ketene (CH2CO) and deuterated ketene (CD2CO) have been measured at the threshold for the production of CH2 (X̃ 3B1) or CD2 (X̃ 3B1) and CO (X̃ 1Σ+) by photofragmentation in a cold jet. The rate constant increases in a stepwise manner as energy increases. This is in accord with the long-standing premise that the rate of a unimolecular reaction is controlled by flux through quantized transition-state thresholds at each energy level for vibrationa
The rotational distributions of CO products from the dissociation of ketene at photolysis energies 10 cm−1 below, 56, 110, 200, 325, 425, 1107, 1435, 1720, and 2500 cm−1 above the singlet threshold (30 116.2 cm−1 ), are measured in a supersonic free jet of ketene. The CO(v″=0) rotational distributions at 56, 110, 200, 325, and 425 cm−1 are bimodal. The peaks at low J′s, which are due to CO from the singlet channel, show that the product rotational distribution of CO product from ketene dissociat
Femtosecond chemical activation of reactions at very high thermal energies, much above the bond energy, is developed in this report. We address the concept of nonstatistical dynamics at such high energies. The approach offers a new direction for probing the dynamics of reactions in their ground state with unique activation, collision-free, and temporally and spatially defined.
Multidimensional facets of the hydrogen tunneling dynamics of phenol excited in S<sub>1</sub> (ππ*) have been unraveled to give particular S<sub>1</sub> vibronic states strongly coupled or actively decoupled to the O-H tunneling coordinate. Strong mode-dependent variation of the tunneling rate measured with picosecond lasers indicates that tunneling probability is extremely sensitive to low-frequency vibrational modes seemingly orthogonal to the O-H elongation coordinate unless the rate of energ
Soret band lifetimes of the free-base tetraphenylporphine (H(2)TPP) and Cu(ii) tetraphenylporphine (Cu(II)TPP) at 408 nm have been directly measured with femtosecond (fs) resolution using the fluorescence-upconversion technique for the first time, giving tau = 68 +/- 15 and 63 +/- 15 fs, respectively, in benzene solvent.
