Jd. Close et al., HELIUM DROPLETS - A NANOSCALE CRYOSTAT FOR HIGH-RESOLUTION SPECTROSCOPY AND STUDIES OF QUANTIZED VORTICITY, Journal of low temperature physics, 111(3-4), 1998, pp. 661-676
In this paper we discuss helium droplets as a nanoscale cryostat for a
variety of fundamental experiments in condensed matter physics. Speci
fically, we describe our recent work on the spectroscopy of silver ato
ms, europium atoms and C-60 in, helium droplets and compare the helium
droplet, as a matrix for low temperature studies of complex systems,
with traditional matrix and gas phase techniques. Further, we discuss
our recent work on the production of ultra-cold metal clusters of silv
er, indium and europium embedded in helium droplets at a temperature (
T=0.37K) two orders of magnitude lower than previously achieved in bea
ms of free metal clusters. This work opens the door to high resolution
spectroscopic studies of metal clusters and, possibly, high resolutio
n studies of the size dependence of their superconducting properties.
We further speculate on a series of experiments where me plan to use s
tandard spectroscopic methods, developed in recent years, to exploit t
he helium droplet for studies of the existence, stability and dynamics
of quantized vortices. Helium droplets may be the ideal system for su
ch studies due to the complete absence of pinning sites that plague ma
ny similar experiments performed in bulk helium.