TY - JOUR
T1 - The dynamics of evaporation from a liquid surface
AU - Maselli, Olivia
AU - Gascooke, Jason
AU - Lawrance, Warren
AU - Buntine, Mark
PY - 2011/9/6
Y1 - 2011/9/6
N2 - We explore the collisional energy transfer dynamics of benzene molecules spontaneously evaporating from an in vacuo water-ethanol liquid beam. We find that rotations are cooled significantly more than the lowest-energy vibrational modes, while the rotational energy distributions are Boltzmann. Within experimental uncertainty, the rotational temperatures of vibrationally-excited evaporating molecules are the same as the ground state. Collision-induced gas phase energy transfer measurements reveal that benzene undergoes fast rotational relaxation, from which we deduce that the rotational temperature measured in the evaporation experiments (200-230 K) is an indication of the translational energy of the evaporate. Conversely, vibrational relaxation of the high frequency mode, ν6, is very inefficient, suggesting that the ν6 temperature (260-270 K) is an indication of the liquid surface temperature. Modelling of the relaxation dynamics by both 'temperature gap' and 'Master Equation' approaches indicates that the equivalent of 150-260 hard-sphere collisions occur during the transition from liquid to vacuum.
AB - We explore the collisional energy transfer dynamics of benzene molecules spontaneously evaporating from an in vacuo water-ethanol liquid beam. We find that rotations are cooled significantly more than the lowest-energy vibrational modes, while the rotational energy distributions are Boltzmann. Within experimental uncertainty, the rotational temperatures of vibrationally-excited evaporating molecules are the same as the ground state. Collision-induced gas phase energy transfer measurements reveal that benzene undergoes fast rotational relaxation, from which we deduce that the rotational temperature measured in the evaporation experiments (200-230 K) is an indication of the translational energy of the evaporate. Conversely, vibrational relaxation of the high frequency mode, ν6, is very inefficient, suggesting that the ν6 temperature (260-270 K) is an indication of the liquid surface temperature. Modelling of the relaxation dynamics by both 'temperature gap' and 'Master Equation' approaches indicates that the equivalent of 150-260 hard-sphere collisions occur during the transition from liquid to vacuum.
UR - http://www.scopus.com/inward/record.url?scp=80052269335&partnerID=8YFLogxK
U2 - 10.1016/j.cplett.2011.06.010
DO - 10.1016/j.cplett.2011.06.010
M3 - Article
SN - 0009-2614
VL - 513
SP - 1
EP - 11
JO - Chemical Physics Letters
JF - Chemical Physics Letters
IS - 1-3
ER -