title: Water dynamics at neutral and ionic interfaces.
abstract: The orientational dynamics of water at a neutral surfactant reverse micelle interface are measured with ultrafast infrared spectroscopy of the hydroxyl stretch, and the results are compared to orientational relaxation of water interacting with an ionic interface. The comparison provides insights into the influence of a neutral vs. ionic interface on hydrogen bond dynamics. Measurements are made and analyzed for large nonionic surfactant Igepal CO-520reverse micelles (water nanopool with a 9-nm diameter). The results are compared with those from a previous study of reverse micelles of the same size formed with the ionic surfactant Aerosol-OT (AOT). The results demonstrate that the orientational relaxation times for interfacial water molecules in the two types of reverse micelles are very similar (13 ps for Igepal and 18 ps for AOT) and are significantly slower than that of bulk water (2.6 ps). The comparison of water orientational relaxation at neutral and ionic interfaces shows that the presence of an interface plays the dominant role in determining the hydrogen bond dynamics, whereas the chemical nature of the interface plays a secondary role.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
authors.forename: Emily E
authors.initials: EE
authors.lastname: Fenn
authors.forename: Daryl B
authors.initials: DB
authors.lastname: Wong
authors.forename: M D
authors.initials: MD
authors.lastname: Fayer
mesh_terms: D006860:Hydrogen Bonding; D006878:Hydroxides / Q000737:chemistry; D008823:Micelles; D013055:Spectrophotometry, Infrared; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D008823:Micelles; D013501:Surface-Active Agents; D014867:Water; C031356:hydroxide ion
references.citation: Proc Natl Acad Sci U S A. 2008 Apr 8;105(14):5295-300
references.pmid: 18381817
references.citation: J Chem Phys. 2004 Dec 22;121(24):12431-46
references.pmid: 15606264
references.citation: J Phys Chem A. 2005 Jul 21;109(28):6154-65
references.pmid: 16833955
references.citation: J Am Chem Soc. 2008 Oct 22;130(42):13927-37
references.pmid: 18823116
references.citation: Phys Rev Lett. 2005 May 6;94(17):178301
references.pmid: 15904342
references.citation: J Am Chem Soc. 2006 Aug 16;128(32):10366-7
references.pmid: 16895392
references.citation: Science. 2006 Feb 10;311(5762):832-5
references.pmid: 16439623
references.citation: J Phys Chem C Nanomater Interfaces. 2007;111(25):8884-8891
references.pmid: 18728757
references.citation: J Am Chem Soc. 2009 Apr 22;131(15):5530-9
references.pmid: 19323522
references.citation: J Phys Chem B. 2007 Dec 27;111(51):14193-207
references.pmid: 18047308
references.citation: J Am Chem Soc. 2007 Nov 14;129(45):13847-56
references.pmid: 17958418
references.citation: J Chem Phys. 2005 Feb 1;122(5):54506
references.pmid: 15740338
references.citation: Chem Rev. 2005 Sep;105(9):3197-219
references.pmid: 16159150
references.citation: Proc Natl Acad Sci U S A. 2007 Oct 23;104(43):16731-8
references.pmid: 17940023
references.citation: J Chem Phys. 2009 Jul 7;131(1):014704
references.pmid: 19586114
references.citation: Phys Rev Lett. 2007 Oct 5;99(14):148301
references.pmid: 17930728
references.citation: J Am Chem Soc. 2009 Jun 17;131(23):8318-28
references.pmid: 19449867
references.citation: J Phys Chem B. 2008 Jul 31;112(30):9112-7
references.pmid: 18610957
references.citation: J Phys Chem B. 2009 Feb 26;113(8):2428-35
references.pmid: 19193030
references.citation: Proc Natl Acad Sci U S A. 2006 Oct 17;103(42):15355-8
references.pmid: 17028175
references.citation: J Phys Chem A. 2006 Apr 20;110(15):4985-99
references.pmid: 16610816
references.citation: J Chem Phys. 2004 May 1;120(17):8107-17
references.pmid: 15267730
references.citation: J Chem Phys. 2006 Sep 7;125(9):094713
references.pmid: 16965111
references.citation: J Phys Chem A. 2006 Jul 27;110(29):9084-8
references.pmid: 16854019
references.citation: J Phys Chem B. 2008 Nov 13;112(45):14230-42
references.pmid: 18942871
references.citation: Proc Natl Acad Sci U S A. 2009 Jan 13;106(2):375-80
references.pmid: 19106293
references.citation: J Phys Chem B. 2009 Jun 25;113(25):8560-8
references.pmid: 19485407
references.citation: J Am Chem Soc. 2007 Nov 21;129(46):14311-8
references.pmid: 17958424
references.citation: Proc Natl Acad Sci U S A. 2003 Oct 14;100(21):12135-40
references.pmid: 14528004
references.citation: J Phys Chem B. 2008 May 1;112(17):5279-90
references.pmid: 18370431