Ultrafast Dynamics in Microemulsions:  Optical Kerr Effect Study of the Dispersed Oil Phase in a Carbon Disulfide−Dodecyltrimethylammonium Bromide−Water Microemulsion

Abstract

The ultrafast, optically-heterodyne-detected optical Kerr effect has been used to investigate the dynamics of the dispersed oil phase of a novel oil-in-water microemulsion. The carbon disulfide-dodecyltrimethylammonium bromide-water (CS 2 -DTAB-H 2 O) system has been characterized by viscosity and conductivity measurements. The results of these measurements are discussed in terms of possible shape changes and interparticle interactions. Ultrafast measurements are reported for several different compositions of the microemulsion. The results are compared and contrasted with the dynamics of neat CS 2 and CS 2 dissolved in n-alkanes. The dynamics of CS 2 dispersed in the microemulsion do not approach those of the neat liquid in any case, even at the highest possible loading, implying that the dynamics in the oil phase are strongly perturbed by the surfactant. The slow (picosecond) diffusive reorientation of the CS 2 does not reflect the macroscopic viscosity of the microemulsion.

Ultrafast dynamics of pyrrolidinium cation ionic liquids

“…Several line shape models have been used to analyze the low-frequency intermolecular part of OHD-RIKES spectrum for molecular liquids. 33,34,38,50,[80][81][82][83][84][85][86][87][88][89][90][91] The low-frequency intermolecular spectrum of liquids contains the interactioninduced ͑translational͒ and librational ͑reorientational͒ motions. [92][93][94][95][96] The recent study by Ryu and Stratt on the intermolecular dynamics and calculated Kerr spectra of benzene and CS 2 liquids provides insight for how we may consider ionic liquids in a way that goes beyond line shape analyses.…”

“…[25][26][27] Spectral sensitivity in the range from 0.1 to 750 cm −1 makes OHD-RIKES a powerful tool to investigate the intermolecular dynamics and interactions in condensed phases. Recently, femtosecond OHD-RIKES has been used for simple molecular liquids, 24,25,[28][29][30] and for more complex condensed phases such as nanoporous glasses, 31,32 microemulsions, 33,34 hydrated peptide and protein solutions, [35][36][37] and polymer solutions. 34,38 Several groups have studied the ultrafast dynamics of aromatic imidazolium ionic liquids using OHD-RIKES.…”

Intermolecular vibrational modes and orientational dynamics of cooperative hydrogen-bonding dimer of 7-azaindole in solution

“…Femtosecond RIKES is now applied to investigate the intermolecular vibrations not only in simple molecular liquids [12][13][14][15][16][17][18] but also in complex condensed phases [19][20][21][22] such as polya) Electronic mail: shirota@faculty.chiba-u.jp. mer liquids, 23 microemulsions, [24][25][26] nanoporous glasses, [27][28][29][30][31][32][33][34] and room temperature ionic liquids. 22,[35][36][37][38][39][40][41] Among these femtosecond RIKES studies, hydrogen-bonding molecular systems are definite targets for extensive research; these systems include aqueous polymer solutions, 25,[42][43][44] peptide solutions, [45][46][47] and protein films.…”

Cation and anion substitution effects on the ultrafast dynamics of interionic interaction in imidazolium based ionic liquids

“…The Fast Fourier Transform (FFT) of the time domain fs-OHD-RIKES signal would offer a low frequency spectrum in the range between 0.1 and 200 cm −1 . The fs-OHD-RIKES has been successfully applied to simple molecular liquids [8][9][10][11] and condensed complex systems [12][13][14][15][16] to explore the low frequency intermolecular interaction. Recently, several research groups have utilized fs-OHD-RIKES to study the interionic interaction of various Ils [17][18][19][20][21][22][23][24][25][26] and obtained useful information about the effects of cation substitution and anion substitution on the low frequency spectra of ILs [23][24][25].…”