• 제목/요약/키워드: Spectroscopic studies

검색결과 510건 처리시간 0.032초

Alkaloids from Panax Ginseng

  • Yong Nam Han;Byu
    • 고려인삼학회:학술대회논문집
    • /
    • 고려인삼학회 1987년도 Proceedings of Korea-Japan Panax Ginseng Symposium 1987 Seoul Korea
    • /
    • pp.75-80
    • /
    • 1987
  • Over twelve alkaloids were detected in the ether-soluble alkaloid fraction of Panax ginseng roots. Among them, three alkaloids were identified as N9-formylharman, ethyl $\beta$-carboline-1-carboxylate and perlolyrine on the basis of chemical and spectroscopic studies. And also spinacine was isolated from the water-soluble fraction of the roots.

  • PDF

Coherent Two-Dimensional Optical Spectroscopy

  • Cho, Min-Haeng
    • Bulletin of the Korean Chemical Society
    • /
    • 제27권12호
    • /
    • pp.1940-1960
    • /
    • 2006
  • Theoretical descriptions of two-dimensional (2D) vibrational and electronic spectroscopy are presented. By using a coupled multi-chromophore model, some examples of 2D spectroscopic studies of peptide solution structure determination and excitation transfer process in electronically coupled multi-chromophore system are discussed. A few remarks on perspectives of this research area are given.

Interfacial Charge and Mass Transfer at Graphene-SiO2 Substrates: Raman Spectroscopic Studies

  • 류순민
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
    • /
    • pp.115.1-115.1
    • /
    • 2014
  • Atom-thick 2-dimensional materials such as graphene, h-BN and MoS2 hold substantial potential for applications in future molecular-scale integrated electronics, transparent conducting membranes, nanocomposites, etc. From a fundamental point of view, 2-dim crystal-solid substrates can also serve as a unique system to study various physicochemical phenomena occurring at low dimensions or interfaces. In this talk, I will present our recent Raman spectroscopy studies on the surface science problems of graphene: interfacial charge transfer, molecular diffusion in confined space and structural deformation.

  • PDF

Studies on the Constituents of the Herbs of Ajuga multiflora (I)

  • Yu, Young-Jun;Do, Jae-Chul;Jung, Keun-Young;Kwon, Soon-Youl;Son, Kun-Ho
    • 생약학회지
    • /
    • 제29권2호
    • /
    • pp.75-78
    • /
    • 1998
  • In the course of phytochemical studies for the aerial parts of Ajuga multiflora, one flavonoid and two iridoid glycosides were isolated and identified as apigenin (1), 8-O-acetylharpagide (2) and harpagide (3) on the basis of spectroscopic evidence.

  • PDF

구상나무의 추출성분에 대한 연구 - 리그난에 관하여 - (Studies on the Extractives of Abies koreana Wilson - Concerned with Lignans -)

  • 김윤근
    • Journal of the Korean Wood Science and Technology
    • /
    • 제25권4호
    • /
    • pp.1-9
    • /
    • 1997
  • The Abies koreana Wilson has been unique species of Korea and has not been clearly investigated about lignans of extractives. This studies have been carried out from the isolation and determination of lignans from alcoholic extractives in its xylem. Six lignans were isolated and their structures were determined by spectroscopic methods. They were two new compounds, (+)-koreslactol and (-)koreanol and four known compounds, lariciresinol p-coumarate, (+)-todolactol C, (-)-${\alpha}$-intermedianol, and (+)-pinoresinol.

  • PDF

Experimental Techniques for Surface Science with Synchrotron Radiation

  • Jonhnson, R.L.;Bunk, O.;Falkenberg, G.;Kosuch, R.;Zeysing, J.
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 1998년도 제14회 학술발표회 논문개요집
    • /
    • pp.17-17
    • /
    • 1998
  • Synchrotron radiation is produced when charged particles moving with relativistic velocities a are accelerated - for example, deflected by the bending magnets which guide the electron or p positrons in circular accelerators or storage rings. By using special focusing magnetic lattices i in the particle accelerators it is possible to make the dimensions of the particle beam very small with a hi맹 charge density which results in a light source with high b디lIiance. Synchrotron light h has important properties which make it ideal for a wide range of investigations in surface s science. The fact that the spectrum of electromagnetic radiation emitted in a bending magnet e extends in a continuum from the 얹r infra red region to hard x-rays means that it is id않I for a v variety of spectroscopic studies. Since there are no convenient lasers, or other really bright l light sources, in the vacuum ultraviolet and soft x-ray re.밍ons the development of synchrotron r radiation has enabled enormous advances to be made in this di펌C비t spectr따 re밍on. P Polarization-dependent measurements, for ex없nple ellipsometry or circular dichroism studies a are possible because the radiation has a well-defined polarization - linear in the plane of orbit w with additional right-circular, or left-circular, components for emission an생es above, or below, t the horizontal, respectively. Since the synchrotron light is emitted from a bunch of charge c circulating in a ring the light is emitted with a well-defined time structure with a short flash of l light every time a bunch passes an exit port. The time structure depends on the size of the ring a and the number and sequence of filling of the bunches. A pulsed light source enables time¬r resolved studies to be performed which provide direct information on the lifetimes and decay m modes of excited states and in addition opens up the possibility of using time of flight t techniques for spectroscopic studies. The fact that synchrotron radiation is produced in a clean u ultrahi야 vacuum environment is of gr않t importance for surce science studies. The current t비rd generation synchrotron light sources provide exceptionally high baliance and stability a and open up possibilities for experiments which would have been inconceivable only a short time ago.

  • PDF