Photodissociation of Linear Carbon Clusters C_n (n = 4−6)

Abstract

The photodissociation of mass-selected linear carbon clusters (C n , n ) 4-6) is studied using fast beam photofragment translational spectroscopy. The photofragment yield (PFY) spectra consist of several continua spanning the whole visible and ultraviolet region. The product mass distributions for dissociation of C n clusters are dominated by C 3 and its partner fragment C n-3 , although some minor channels are also identified for dissociation of C 4 and C 5 clusters. Translational energy P(E T ) distributions for the C 3 + C n-3 channel were measured at several photolysis energies. The PFY spectra and P(E T ) distributions indicate that multiphoton dissociation occurs at photon energies below the dissociation threshold and that both single-photon and multiphoton dissociation occur above the threshold. The one-photon components of the P(E T ) distributions can be modeled by phase space theory (PST), suggesting that photoexcitation is followed by internal conversion to the ground state. The PST analysis yields dissociation energies for C n f C 3 + C n-3 in reasonable agreement with recent Knudsen effusion mass spectrometry measurements.

Statistical universal branching ratios for cosmic ray dissociation, photodissociation, and dissociative recombination of the C, CH and C3H2neutral and cationic species

“…Figure 8 presents fragmentation BR for C 4 , C 5 , and C 6 carbon clusters obtained by photodissociation and those from HVC-CT. In the reported photodissociation experimental results (Choi et al 2000), the incident photon energy has been varied up to 6 eV with some contribution of multi-photon absorption. The horizontal bars on these measurements correspond to a variation of the BRs with the different photon energies.…”

State-resolved translation energy distributions for NCO photodissociation

“…The details of determining translational energy distributions using PST have been described in detail previously. [42][43][44] Our application of PST assumes a long-range potential V(r) ϭϪC 0 /r 6 , that the vibrational levels are described by the harmonic oscillator approximation, and an initial parent temperature of 50 K. Finally, the calculated PST distributions have been convoluted with a Monte Carlo simulation program in order to account for the apparatus parameters. 28 The translational energy distributions determined from PST are expected to agree with the measured P(E T ) distributions if the dissociation process is barrierless and statistical.…”

Ionization potentials, dissociation energies and statistical fragmentation of neutral and positively charged small carbon clusters

“…The decay of excited small carbon clusters has been experimentally widely studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. In these experiments, the loss of neutral C 3 has been found to be the dominant dissociation process for both charged and neutral clusters.…”