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Single‐molecule Spectroscopy: Exploring Heterogeneity in Chemical and Biological Systems
Author(s) -
Ghosh Shirsendu,
Bhattacharyya Kankan
Publication year - 2016
Publication title -
the chemical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.61
H-Index - 78
eISSN - 1528-0691
pISSN - 1527-8999
DOI - 10.1002/tcr.201500214
Subject(s) - chemical physics , ionic liquid , molecule , diffusion , spectroscopy , ionic bonding , self healing hydrogels , materials science , chemistry , nanotechnology , analytical chemistry (journal) , ion , organic chemistry , physics , thermodynamics , quantum mechanics , catalysis
Many chemical and biological systems are heterogeneous in the molecular length scale (∼ 1 nm). Heterogeneity in many chemical systems and organized assemblies may be monitored using single‐molecule spectroscopy (SMS). In SMS, the size of the focal spot (i.e., the smallest region to be probed) is nearly half of the excitation wavelength (λ/2, i.e., 200–375 nm) for visible light (400–750 nm). We discuss how one can get spatial resolutions better than 200 nm using molecules as nanometric probes. We show that polymer hydrogels, lipid vesicles, room temperature ionic liquids (RTILs), and binary liquid mixtures exhibit such heterogeneity. Another important observation is solute‐dependent friction in RTILs. In an RTIL, diffusion of an ionic solute is slower than that of a neutral solute.