We use the liquid microjet technique coupled with laser spectroscopy to measure the rotational and vibrational energy content of benzene spontaneously evaporating from a water?ethanol solution. We find different temperatures for rotation (206 K) and for the two low-lying vibrational modes, ?6 (256 K) and ?16 (229 K). Collision-induced energy-transfer measurements reveal efficient rotational relaxation, from which we deduce that the rotational temperature indicates the translational energy of the evaporate. Conversely, the relaxation of ?6 is very inefficient, suggesting that the ?6 temperature indicates the surface temperature of the liquid. Modeling the relaxation of ?16 indicates that >102 collisions are occurring during the transition from liquid to vacuum, which is an order of magnitude more than has been reported to occur in the gas phase immediately above the liquid surface. Our results reveal that evaporative molecular energy transfer involves many collisions, resulting in moderate collisional cooling as molecules pass from liquid to vapor.
(private-note)Sören showed me this towards the end of 2011 as I'd been talking about the temperatures characterizing the `freezing-out' of degrees of freedom evident in the caloric equations of state of polyatomic gases. He thought this was relevant, but on inspection I think they're talking about something else. They're talking about nonequilibrium situations in which it does not make sense to characterize the different degrees of freedom as having the one temperature at a point in space and instant in time; i.e. their temperatures are dynamically variables whereas I was talking about temperature-valued constants characterizing the material.
%0 Journal Article
%1 citeulike:10227939
%A Maselli, Olivia J.
%A Gascooke, Jason R.
%A Lawrance, Warren D.
%A Buntine, Mark A.
%B The Journal of Physical Chemistry C
%D 2008
%I American Chemical Society
%J J. Phys. Chem. C
%K 92e10-molecular-structure 68u20-computational-simulation
%N 2
%P 637--643
%R 10.1021/jp804270v
%T Benzene Internal Energy Distributions Following Spontaneous Evaporation from a Water−Ethanol Solution
%U http://dx.doi.org/10.1021/jp804270v
%V 113
%X We use the liquid microjet technique coupled with laser spectroscopy to measure the rotational and vibrational energy content of benzene spontaneously evaporating from a water?ethanol solution. We find different temperatures for rotation (206 K) and for the two low-lying vibrational modes, ?6 (256 K) and ?16 (229 K). Collision-induced energy-transfer measurements reveal efficient rotational relaxation, from which we deduce that the rotational temperature indicates the translational energy of the evaporate. Conversely, the relaxation of ?6 is very inefficient, suggesting that the ?6 temperature indicates the surface temperature of the liquid. Modeling the relaxation of ?16 indicates that >102 collisions are occurring during the transition from liquid to vacuum, which is an order of magnitude more than has been reported to occur in the gas phase immediately above the liquid surface. Our results reveal that evaporative molecular energy transfer involves many collisions, resulting in moderate collisional cooling as molecules pass from liquid to vapor.
@article{citeulike:10227939,
abstract = {{We use the liquid microjet technique coupled with laser spectroscopy to measure the rotational and vibrational energy content of benzene spontaneously evaporating from a water?ethanol solution. We find different temperatures for rotation (206 K) and for the two low-lying vibrational modes, ?6 (256 K) and ?16 (229 K). Collision-induced energy-transfer measurements reveal efficient rotational relaxation, from which we deduce that the rotational temperature indicates the translational energy of the evaporate. Conversely, the relaxation of ?6 is very inefficient, suggesting that the ?6 temperature indicates the surface temperature of the liquid. Modeling the relaxation of ?16 indicates that >102 collisions are occurring during the transition from liquid to vacuum, which is an order of magnitude more than has been reported to occur in the gas phase immediately above the liquid surface. Our results reveal that evaporative molecular energy transfer involves many collisions, resulting in moderate collisional cooling as molecules pass from liquid to vapor.}},
added-at = {2017-06-29T07:13:07.000+0200},
author = {Maselli, Olivia J. and Gascooke, Jason R. and Lawrance, Warren D. and Buntine, Mark A.},
biburl = {https://www.bibsonomy.org/bibtex/2aa5c9b537189a1d9aab70bab4f28f548/gdmcbain},
booktitle = {The Journal of Physical Chemistry C},
citeulike-article-id = {10227939},
citeulike-linkout-0 = {http://dx.doi.org/10.1021/jp804270v},
citeulike-linkout-1 = {http://pubs.acs.org/doi/abs/10.1021/jp804270v},
comment = {(private-note)S\"{o}ren showed me this towards the end of 2011 as I'd been talking about the temperatures characterizing the `freezing-out' of degrees of freedom evident in the caloric equations of state of polyatomic gases. He thought this was relevant, but on inspection I think they're talking about something else. They're talking about nonequilibrium situations in which it does not make sense to characterize the different degrees of freedom as having the one temperature at a point in space and instant in time; i.e. their temperatures are dynamically variables whereas I was talking about temperature-valued constants characterizing the material.},
day = 19,
doi = {10.1021/jp804270v},
interhash = {d9a7cc55df81d8683210837d3e0cf8c1},
intrahash = {aa5c9b537189a1d9aab70bab4f28f548},
journal = {J. Phys. Chem. C},
keywords = {92e10-molecular-structure 68u20-computational-simulation},
month = dec,
number = 2,
pages = {637--643},
posted-at = {2012-01-15 23:43:42},
priority = {2},
publisher = {American Chemical Society},
timestamp = {2019-05-01T06:14:12.000+0200},
title = {{Benzene Internal Energy Distributions Following Spontaneous Evaporation from a Water−Ethanol Solution}},
url = {http://dx.doi.org/10.1021/jp804270v},
volume = 113,
year = 2008
}