Gallium Arsenide Clusters and their Interfacial Physics and Chemistry
Abstract
Gallium arsenide clusters have been studied on a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer with an external supersonic cluster source. Reaction of GaAs cluster cations with ammonia revealed that all cluster cations larger than seven atoms were most reactive near the 1/1 composition ratio of gallium/arsenic. The results suggest that even at this small size, the clusters begin to adopt the alternating gallium/arsenic bonding arrangement characteristic of bulk GaAs crystal surfaces where gallium-arsenic bonding activates gallium atoms for ammonia chemisorption. With excess NH3, GaAsy (NH3 )z( +) with the same GaAs composition (x and y) was observed with several values of z, which is explained in terms of the existence of multiple isomers of GaAs clusters. However, the anions were found to be inert toward NH3. Nitric oxide was found to etch singly charged GaxAsy (x + y = 9 to 16) clusters. A pronounced even-odd alternation in cluster ion reactivity towards NO was observed with the odd numbered cluster ions which are believed to be closed shell singlets being much less reactive than the even numbered cluster ions which are of necessity open shell species. The local density calculations of small GaxAsy (x + y < 10) have been carried out. Multiple low energy structures were found, and the electronic properties are in agreement with experimental results.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 15, 1992
- Accession Number
- ADA249565
Entities
People
- Frank K. Tittel
- Richard E. Smalley
- Robert F. Curl
Organizations
- Rice University