Fragmentation of I2- (CO2)n (n= 1-30) by its collision on a silicon surface was investigated by measuring the fragment anions and their translational energy parallel to the surface (surface-parallel translational energy) in a tandem time-of-flight mass spectrometer equipped with a collision chamber evacuated down to ∼ 10-8 Pa. At the collision energy (per 12-) of 50 eV and the incident angle of 26° with respect to the surface normal, the distributions of the surface-parallel translational energies of the fragment anions from a given parent cluster anion were found to obey the one-dimensional Maxwell-Boltzmann distribution with the same translational temperature, Ts∥ The results show that the cluster anion and its neighboring surface atoms reach quasiequilibrium before the fragment anions leave the surface. A general increasing trend of Ts∥ (6000-12 000 K) with n is interpreted as an increasing extent of cluster-impact heating with n, while the reduction of Ts∥ in the 13≤n≤∼ 19 range is attributable to efficient transmission of the I- and I2- translational energies to the CO2 solvent cage. The effective volume and pressure of I2-(CO2)n colliding on the surface were estimated; at n = 10, the volume and the pressure were 100 nm3 and 10 MPa, respectively.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry