PHYSICS/BK21 SEMINAR[09.06.10]pm4:00~
관련링크
본문
"
“Coherent reflection and focusing of
He atom beams from rough surfaces
at near-grazing incidence”
♦Speaker : Dr. Bum Suk Zhao (Max-Planck-Institute, Germany)
♦Place : Physics Seminar Room (Science Bldg, 3-201)
♦Date & Time : June, 10(Wed) 4:00 ~ 5:00 pm
Abstract
We observe coherent reflection of thermal He atom beams from various microscopically-rough
surfaces at grazing incidence. For a sufficiently small normal component kz of the incident
wave-vector of the atom the reflection probability is found to be a function of kz only. This
behavior is explained by quantum-reflection at the attractive branch of the Casimir-van der
Waals interaction potential [1]. For larger values of kz the reflection probability is found to
increase with parallel component kx for a given kz. The material specific kx dependence is
discussed in terms of an effective averaging-out of the surface roughness and the atom-surface
Casimir-van der Waals potential under grazing incidence conditions. The coherent reflection at
grazing incidence is exploited to focus He atom beams in one dimension down to 2 ㎛ with a
Concave cylindrical mirror. The mirror is made out of quartz and has a curvature radius of 78 m.
The focal length can be adjusted by varying the incidence angle. With a relatively large focal length,
the spot size gets larger with increasing source size and increasing deBroglie-wavelength. On the
other hand, when the focal length is adjusted to a small value by decreasing the incidence angle,
the focal spot size is mainly determined by spherical aberration of the mirror.
Contact Person : Prof. Nam Ki Lee (054-279-2097, nklee@postech.ac.kr)
"
“Coherent reflection and focusing of
He atom beams from rough surfaces
at near-grazing incidence”
♦Speaker : Dr. Bum Suk Zhao (Max-Planck-Institute, Germany)
♦Place : Physics Seminar Room (Science Bldg, 3-201)
♦Date & Time : June, 10(Wed) 4:00 ~ 5:00 pm
Abstract
We observe coherent reflection of thermal He atom beams from various microscopically-rough
surfaces at grazing incidence. For a sufficiently small normal component kz of the incident
wave-vector of the atom the reflection probability is found to be a function of kz only. This
behavior is explained by quantum-reflection at the attractive branch of the Casimir-van der
Waals interaction potential [1]. For larger values of kz the reflection probability is found to
increase with parallel component kx for a given kz. The material specific kx dependence is
discussed in terms of an effective averaging-out of the surface roughness and the atom-surface
Casimir-van der Waals potential under grazing incidence conditions. The coherent reflection at
grazing incidence is exploited to focus He atom beams in one dimension down to 2 ㎛ with a
Concave cylindrical mirror. The mirror is made out of quartz and has a curvature radius of 78 m.
The focal length can be adjusted by varying the incidence angle. With a relatively large focal length,
the spot size gets larger with increasing source size and increasing deBroglie-wavelength. On the
other hand, when the focal length is adjusted to a small value by decreasing the incidence angle,
the focal spot size is mainly determined by spherical aberration of the mirror.
Contact Person : Prof. Nam Ki Lee (054-279-2097, nklee@postech.ac.kr)
"
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