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Weight loss and isotopic shifts for water drops frozen on a liquid nitrogen surface
Author(s) -
Eguchi Keiko,
Abe Osamu,
Hiyama Tetsuya
Publication year - 2008
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3724
Subject(s) - chemistry , liquid nitrogen , chromatography , liquid water , nitrogen , analytical chemistry (journal) , organic chemistry , thermodynamics , physics
A liquid nitrogen freezing method was used to collect raindrops for the determination of isotope‐size distribution. Water drops that fall onto a surface of liquid nitrogen stay suspended for 10 to 20 s, until their temperature reaches the Leidenfrost point (126 K). As their temperature falls to the freezing point, they release their heat by thermal conduction. At the freezing point, latent heat of fusion is released, along with a significant loss of water. After freezing completely, the ice droplets stay suspended, cooling by thermal conduction until they reach the Leidenfrost point. They then lose buoyancy and start sinking. Consistent isotopic changes of 1.5 ± 0.4 and 0.33 ± 0.05‰ for hydrogen and oxygen, respectively, were found for droplets with radii between 1.0 and 1.5 mm. Isotope fractionation appeared to occur at the same time as water loss, as the droplets were freezing, in what was probably a kinetic effect. Copyright © 2008 John Wiley & Sons, Ltd.