Determining if a system is heterogeneous: the analysis of single molecule rotational correlation functions and their limitations.
Single molecule spectroscopy can be utilized to measure distributions of individual molecular properties that may be averaged out in the ensemble measurement. For example, complex dynamics in disordered systems can be investigated by observing single molecule rotations via fluorescence spectroscopy. The rotational time of a single transient can be calculated from the correlation function of the reduced linear dichroism signal which fluctuates over time as the molecule reorients in its surroundings. Distributions of rotational time constants can be used to characterize the heterogeneity of molecular environments in the material. This paper reviews some theoretical studies on (1) the high numerical aperture effects on the final correlation function, and how it can be related to optical anisotropy decays in a bulk measurement; (2) the statistical errors resulting from the finite observation length that will propagate into distributions of rotational times. These lead to the discussions on how to interpret correctly the distribution of properties measured from a set of single molecule data, and to determine if in fact the system is heterogeneous.
Wei
Chia-Yin Joyce
CY
Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station, Austin, TX 78712, USA.
Lu
Chun-Yaung
CY
Kim
Yeon Ho
YH
Vanden Bout
David A
DA
Annu Rev Phys Chem. 2000;51:99-128
11031277
Phys Rev Lett. 2005 Oct 21;95(17):173001
16383825
Phys Rev Lett. 2002 Jul 8;89(2):026101
12097008
Phys Rev Lett. 2004 Nov 12;93(20):203001
15600920
Acc Chem Res. 2005 Dec;38(12):923-31
16359164
Opt Lett. 2001 Feb 15;26(4):211-3
18033550
J Chem Phys. 2006 Sep 28;125(12):124701
17014194
J Am Chem Soc. 2003 Mar 5;125(9):2730-5
12603162
J Chem Phys. 2004 Jun 15;120(23):11082-9
15268138