ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
In this paper, the structure of CO2 clusters made of less than a hundred of molecules is studied by means of electron diffraction experiments and molecular dynamics simulations. According to previous works, CO2 clusters are expected to undergo a transition in this size range, from an icosahedral structure to the bulk cubic structure. Electron diffraction patterns have been recorded from clusters produced in a free jet expansion of gaseous CO2. These patterns provide evidence of a structural change occurring in clusters made of a few tens of molecules. (CO2)N models, with 13〈N〈80, have been constructed in the cubic structure and annealed through a molecular dynamics calculation. Calculated diffraction functions show significant changes for a critical size of about 30 molecules per cluster. In the N=25 model, carbon atoms exhibit a polyicosahedral arrangement, similar to the one already identified in argon cluster models. In the N=32 model, most of the molecules build up a cubic lattice, meanwhile some of them adopt a pentagonal arrangement allowing a higher cluster stability. In addition to what has been observed previously, the present study confirms that the transformation from an icosahedral to a crystalline structure is a general process which occurs during the growth of van der Waals clusters made of small molecules. The relation between the critical size and the molecular species is briefly discussed. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.472237
Permalink