Seung Koo Shin, Ph.D.

Associate Professor
Department of Chemistry
Division of Molecular and Life Sciences
Experimental Physical Chemistry, Quantum Chemistry

Publications Abstract
E-mail skshin@postech.ac.kr
Phone +82-54-279-2123(office)
          +82-54-279-8153(lab.)
Laboratory FT-ICR lab. 

Profile |  Research Interests  |  Selected Publications  | Lab. Members

Profile

Research Interests

Our research projects deal primarily with mass spectrometric studies of energetics, kinetics, and dynamics of photoinitiated reactions of solvated ions in the absence of bulk solvents, and biological applications of mass spectrometric techniques to the peptide mass mapping and protein folding.  Experimental setups inculde a 5-T Fourier transform ion cyclotron resonance (FT-ICR), a 3-T FT-ICR, a 1-T FT-ICR, 1 reflectron time-of-flight, and a multiphoton ionization mass spectrometer.  Theoretical studies are also carried out extensively to corroborate experiments.
FT-ICR mass spectrometry is applied to the studies of the dynamics and spectroscopy of solvated triple ions, photoinduced processes in size-selected quantum dots, and identification of protein components that bind to the centromere of the yeast chromosome.  FT-ICR mass spectrometry allows the trapping of ions in the gas phase and thereby enables accurate mass measurements.  When combined with MALDI, the ion-trapping capability of FT-ICR allows the studies of chemical and spectroscopic properties of ions that are present in electrolyte solutions or in colloidal aggregates of semiconductor quantum dots.  The high mass-resolution capability of FT-ICR also permits the high-accuracy mass measurement of mass-selected ions for the identification of proteins.

Chemical Reaction Dynamics of Molecular and Ionic Clusters and Protein Folding
Time- and product-resolved photodissociation spectroscopy (TRRPD) using FT-ICR spectrometry allows the determination of activation energy and entropy from energy-selected unimolecular dissociation of mass-selected ions.  Energy- and/or state-selective TPRPD methodology was developed and applied to stdy the formation of the tropylium ion, silacyclotrienyl cation, and azafullerene cations to elucidate the mechanism of photofragmentation.  TPRPD spectroscopy is also being applied to photodissociation of solvated ionic complexes, quantum dot clusters, and protein folding.

Quantum Dots, Rings, and Photon Harvesting Quantum Assembly
This project deals primarily with the synthesis and characterization of a quantum-ring electron-pool molecular assembly to harvest photons into a chemical energy.  The goal of the project is to develop artificial photosystems mimicing the photosynthesis in plant that converts a photon energy of sun-light to a chemical energy.  To this end, the semiconductor quantum dot clusters are assembled to form a quantum-ring that acts as the light-harvesting antenna.  The quantum ring structure is designed to absorb photons in a selected wavelength range by tailoring the bandgap of quantum dots.  This quantum-ring structure allows a resonant electron transfer among its quantum-dot elements, which permits the storage of the photon energy in the quantum ring and enables the harvesting of light.  To convert a photon energy to a chemical energy, an electron pool can be combined with the quantum-ring structure to form a quantum-ring-electron-pool molecular assembly.  We will synthesize the II-VI semiconductor quantum dot clusters and quantum rings, characterize their photochemical and photophysical properties, study the exciton dynamics, examine the chemical bonding and photochemistry of ionized quantum dot clusters, and investigate the luminescence of single quantum dot clusters. The quantum-ring-electron-pool assembly will be applied to the studies of photocatalysts, photosensors, and biosensors.

Peptide Mass Mapping
The high-resolution mass spectrometry also finds a growing number of applications in biology.  Two recent developments have now enabled the identification of very small amounts of material in gel bands.  First, with the completion of the genome sequencing project, the sequence of every protein is now available in public databases.  Second, peptide mass maps of very small amounts of enzymatically digested proteins obtained by MALDI mass spectrometry are now sufficiently accurate to screen databases and identify proteins whose sequence is already known.  Thus, the accurate mass measurement allows the identification of unknown proteins as well as the post-translational modification site in proteins.  We apply the mass spectrometric techniques to the identification of unknown proteins by peptide mass mapping.

Selected Publications 

1. S. K. Shin and S.-J. Han, "Application of Sustained Off-Resonance Irradiation: The Beat Frequency Measurement and Radial Separation of Mass-Selected Ions," J. Am. Soc. Mass Spectrom. 8, 86-89 (1997).
2. B. Kim and S. K. Shin, "Time- and Product-Resolved Photodissociations of o-, m-, and p-Bromotoluene Radical Cations," J. Chem. Phys. 106, 1411-1417 (1997).
3. S-J. Han and S. K. Shin, "The Space Charge Effect on FT-ICR Signals: Experimental Observation and Trajectory Simulations," J. Am. Soc. Mass Spectrom. 9, 319-326 (1997).
4. R. L. Jarek, R. J. Flesher and S. K. Shin, "Kinetics of Internal Rotation of N,N-Dimethylacetamide: A Spin-Saturation Transfer Experiment,"  J. Chem. Educ. 74, 978-982 (1997).
5. R. L. Jarek and S. K. Shin, "Experimental and Theoretical Studies of the Silacycloheptatrienyl Cation Formation from Phenylsilane,"J. Am. Chem. Soc. 119, 6376-6383 (1997).
6. R. L. Jarek, and S. K. Shin, "Solvations of the Li⁺BrLi⁺ Triple Ion in the Gas Phase, "J. Am. Chem. Soc. 119, 10501-10508 (1997).
7. S. K. Shin, "Relative Stabilities of o-, m-, and p-Tolyl Ions, "Chem. Phys. Lett. 280, 260-265 (1997).
8. R. L. Jarek, S. C. Denson, and S. K. Shin, "Solvations of the Li⁺ClLi⁺ Triple Ion in the Gas Phase," J. Chem. Phys. 109, 4258-4266 (1998).
9. R. L. Jarek, T. D. Miles, M. L. Trester, S. C. Denson, S. K. Shin, Solvation of Li+ by Acetone, THF, and Diethyl Ether in the Gas Phase and the Ion-Molecule Association Mechanism, J. Phys. Chem. A, The Goddard Festschrift Issue, in press (2000).
10. H. S. Son, K. Lee, S. K. Shin, J. K. Ku, Radiative Lifetimes of the FeO Orange System, Chem. Phys. Lett. In press (2000)
11. D, Belkic, P. A. Dando, J. Main, H. S. Taylor, S. K. Shin, Decimated Signal Diagonalization for Ion Cyclotron Resonance Spectroscopy, Chem. Phys. Lett. Submitted (2000).

Lab. Members

Division of Molecular & Life Sciences| POSTECH