Issue 2, 2013

Twin-focus photothermal correlation spectroscopy

Abstract

We introduce a novel concept for optical correlation spectroscopy of non-fluorescent absorbing nano-particles termed twin-focus photothermal correlation spectroscopy (Twin-PhoCS). This method exhibits a unique axial sensitivity, allowing for either the measurement of very slow axial dynamics or the determination of axial heterogeneities on sub-diffraction limited length-scales. To this end, the photothermal nano-lensing mechanism [Markus Selmke, Romy Schachoff, Marco Braun, and Frank Cichos, ACS Nano, 2012, 6(3), 2741] provides two sharply separated detection-subvolumes, comprising the twin-focus. The achieved axial sensitivity is superior to single detection-volume or dual-focus based fluorescence correlation spectroscopies. We demonstrate the sensitivity by measuring radiation-pressure induced flow velocities of diffusing 14 nm gold-colloids down to 10 nm ms−1 with the help of the provided analytical correlation functions.

Graphical abstract: Twin-focus photothermal correlation spectroscopy

Supplementary files

Additions and corrections

Article information

Article type
Paper
Submitted
05 Sep 2012
Accepted
02 Nov 2012
First published
23 Nov 2012

RSC Adv., 2013,3, 394-400

Twin-focus photothermal correlation spectroscopy

M. Selmke, R. Schachoff, M. Braun and F. Cichos, RSC Adv., 2013, 3, 394 DOI: 10.1039/C2RA22061J

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