korea inu

Single-Molecule Spectroscopy Lab

 Name   Cheong, Byeong-Seo
 Office   No. 05-449 / TEL : +82-32-835-8235
 Lab   Single-Molecule Spectroscopy Lab. / No. 05-413 / TEL : +82-32-835-4562
 E-mail   bcheong@incheon.ac.kr

 Research Fields

• main research field
   - Physical Chemistry

• detail research field
   - Chemical Reaction Dynamics, Photophysical Chemistry, Computational Chemistry


• B.Sc., Seoul National University, Department of Chemistry, Korea, 1983
• M.S., Seoul National University, Korea, 1985
• Ph.D., The Ohio State University, USA, 1993

 Research Interests

The primary research objective of Professor Cheong and his group is to gain better understanding of properties, intermolecular interactions, and dynamics of the various complex molecular systems by using modern spectroscopic methods.
In particular, recent efforts are devoted to the field of 'single-molecule spectroscopy', and by spectroscopic measurements on ‘single’ molecules, the research intends to elucidate the properties and behaviors of single molecules, which were not observed in the conventional bulk measurements.
Bulk or ensemble measurements yield the 'average' value of the experimental parameter of our interest about the large number of molecules. On the other hand, single-molecule measurements remove ensemble averaging completely, and enable to see the real 'distribution' of possible values for the experimental parameter measured.
It is clear that such distribution of values gives much more and direct information than the average value alone.

 Laboratory Facilities

Pulsed Laser System Pulsed Nd:YAG laser (Spectra Physics GCR-150, 30 Hz, SHG [532 nm] and THG [355 nm]) Tunable Pulsed Dye laser (Lumonics HD-300) This pulsed laser system is used in spectroscopic investigation of many chemically interesting systems.

Since the laser pulse generated has a less than 10 nanosecond pulse width, the laser system can also be used for the lifetime measurement of molecules with a relatively long lifetime, for example, transition metal complexes.

Single-Molecule Fluorescence Microscopy Setup DPSS CW Laser (CrystaLaser GCL-025-L, λ = 532nm, 25mW) Inverted Microscope (Olympus IX71, Objective UPLFLN 100x/1.30, oil-immersion) EMCCD (Andor iXon+ DU-897, 512×512 pixels, back-illuminated) This fluorescence microscopy setup is used for the single-molecule detection and single-molecule spectroscopy.

The excitation light is provided with a diode pumped solid-state Nd:YAG laser operating at 532 nm. The excitation light is directed into the inverted microscope, and the microscope objective with a high numerical aperture is used to excite the sample molecules as well as to collect the resulting fluorescence.

Fluorescence from singlemolecules is imaged with a highly sensitive EMCCD camera. The fluorescence images are usually collected at a fixed time interval, and the series of images are analyzed to extract information on various single-molecule properties and behaviors.