Superfluid helium droplets:a uniquely cold nanomatrix for molecules and molecular complexes

摘要

Herein,recent experiments on the spectroscopy and chemical reactions of molecules and complexes embedded in helium drop-lets are reviewed.In the droplets,a high spectroscopic resolution,which is comparable to the gas phase is achieved,while an isothermal low-temperature environment is maintained by evap-orative cooling at "T=0.37 K (~4He droplets) or 0.15 K (~3He droplets),lower than possible in most solid matrices.Thus the helium -droplet technique combines the benefits of both the gas phase and the classical matrix-isolation techniques.Most important the suPerfluid helium facilitates binary encounters,and absorbs the released binding energy upon recombination.Thus the droplet can be viewed as an isothermal nanoscopic reactor,which isolates single molecules,clusters,or even a single reactive encounter at ultralow temperatures.