Photothermal signal distribution analysis (PhoSDA)

Abstract

Photothermal correlation spectroscopy (PhoCS) is a powerful counterpart to fluorescence correlation spectroscopy (FCS). Using PhoCS it is possible to probe the dynamics of non-fluorescent and non-bleaching ultra-stable metal-nanoparticles in solution and biological specimen, where they can be used as tracers and markers. This paper complements the absorption correlation method by a histogram analysis framework, the photothermal signal distribution analysis (PhoSDA). It is hereby possible to extract individual absorbent tracer concentrations, size dispersions, heterogeneous populations and focal geometry parameters which are otherwise inaccessible by correlation analysis.

Photothermal microscopy: optical detection of small absorbers in scattering environments

“…Correlation between positive and negative signals allows the measurement of slow axial dynamics (10 nm ms −1 ), which could be of interest to detect directed motion of gold labelled biomolecules in cells for example. In addition, study of PhI signal histogram can reveal properties of the diffusing particles such as concentration, size distribution, etc., from the same dataset (Selmke et al ., ).…”

Imaging nano-objects by linear and nonlinear optical absorption microscopies

“…This cannot be done for the transient absorption experiments described above: when the probe is resonant to a transition of the sample, high probe powers ultimately destroy the sample [40]. PHI can be used to generate spectra by scanning the wavelength of the pump beam [7,8], but the main applications of these measurements have been for ultrasensitive detection [5,7,26,47,48] and correlation measurements [121,126,128,130,143,144].…”