Picosecond response of sodium clusters on dielectric substrates

• Published in: Optics communications Vol. 161; no. 1; pp. 42 - 46
• Main Authors: Klein-Wiele, J.-H., Simon, P., Rubahn, H.-G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.1999; Elsevier Science
• Subjects: Atomic and molecular clusters; Atomic and molecular physics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Nonlinear optics; Optical properties of clusters; Optics; Physics; Studies of special atoms, molecules and their ions; clusters; 36.40.+d; 42.65.–k; Second harmonic generation; Sodium; Optical properties; Adsorbed state; fs range; Lithium fluorides; Experimental study; Pulsed lasers; Nonlinear optics; Mica; Atomic clusters
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/S0030-4018(98)00675-0

A strong increase of second-order nonlinear optical signal intensity due to electromagnetic field enhancement, in combination with femtosecond nonlinear optical pump–probe techniques facilitates measuring relaxation time constants τ r in large Na n ( n≈10 5–10 7) clusters, bound to insulator surfaces. Time constants of τ r≈1.8 ps for Na n clusters on mica and τ r≈1.1 ps for Na clusters on lithium fluoride are found. The difference is attributed to either morphological changes or the different thermal properties of the substrates. The subpicosecond-part of the time-resolved response is seen to be dominated by the field-enhancement effect, but is otherwise independent of cluster size for mean radii between 12 and 100 nm.