Berlin 2001 – wissenschaftliches Programm
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AMPD: EPS AMPD
AMPD 5: Sitzung 5
AMPD 5.5: Vortrag
Mittwoch, 4. April 2001, 11:20–11:45, H105
LIGHT–INDUCED ATOMIC DESORPTION: GENERAL FEATURES, INTERPRETATION AND APPLICATIONS — •E. Mariotti1, S.N. Atutov2,3, V. Biancalana1, A. Burchianti1, R. Calabrese2, V. Guidi2, B. Mai2, C. Marinelli1, L. Tomassetti2, and L. Moi1 — 1INFM–UdR Siena, Dipartimento di Fisica – Università di Siena Via Banchi di Sotto 55, 53100 Siena, Italy — 2Dipartimento di Fisica – Università di Ferrara, Italy — 3Permanent address: Institute of Automation and Electrometry, Novosibirsk, Russia
Light induced atomic desorption (LIAD) is an impressive manifestation of a new class of phenomena involving alkali atoms, dielectric films and light. LIAD consists of a huge emission of alkali atoms (experimentally proved for sodium, potassium, rubidium and cesium) from siloxane films when illuminated by very weak laser or ordinary light. Most of the experiments have been performed in glass cells suitably coated by a thin film (of the order of 0.01mm) either of poly – (dimethylsiloxane) (PDMS), a polymer, or of octamethylcyclotetrasiloxane (OCT), a crown molecule. LIAD is a combination of two processes: direct photo – desorption from the surface and diffusion within the siloxane layer. The photo – desorbed atoms are replaced by fresh atoms diffusing to the surface. Moreover, from the experimental data it comes out that the desorbing light increases the diffusion coefficient and hence the atomic diffusion. To our knowledge this is the first time that such an effect is clearly observed, measured and discussed: LIAD represents a new class of photo–effects characterized by two simultaneous phenomena due to the light: surface desorption and fastened bulk diffusion.
In the talk, a review of the main LIAD features will be given; the effect will be compared to other light – induced desorption processes, and its specific character will be shown. A theoretical model will be discussed. In the second part, attention will be payed to applications: the possibility of obtaining controlled vapor sources and the enhancement of trapping efficiency in a MOT.
[1] A.Gozzini, F.Mango, J.H.Xu, G.Alzetta, F.Maccarrone, R. Bernheim, Nuovo Cimento D15, 709 (1993).
[2] M.Meucci, E.Mariotti, P.Bicchi, C.Marinelli, L.Moi, Europhys. Lett. 25, 639 (1994).
[3] E.Mariotti, M.Meucci, P.Bicchi, C.Marinelli, L.Moi, Opt. Commun. 134, 121 (1997).
[4] S.N.Atutov et al. Phys.Rev.A 60, 4693 (1999).