Abstract

The depth profiling capability of Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) has been used to distinguish spectroscopically between the surface layer (cuticle) and the interior (cortex) of intact keratin fibers. The thermal diffusion lengths of wool and hair fibers, calculated as a function of the wavenumber and optical scanning velocity of the interferometer, indicate a depth resolution of the order of a micrometer. Shifts in the amide I and II bands to lower wavenumbers were observed with increasing velocity of the interferometer, consistent with differences in protein structure between the bulk and surface regions of the fiber. On the basis of these spectral changes, the location of the cuticle/cortex interface below the fiber surface can be determined.

Depth-resolved chromophore analysis of bovine retina and pigment epithelium by photoacoustic spectroscopy

François Boucher, Roger M. Leblanc, Sylvie Savage, and Bruno Beaulieu
Appl. Opt. 25(4) 515-520 (1986)

Non-invasive depth profiling of the stratum corneum in vivo using confocal Raman microscopy considering the non-homogeneous distribution of keratin

Maxim E. Darvin, Chun-Sik Choe, Johannes Schleusener, and Jürgen Lademann
Biomed. Opt. Express 10(6) 3092-3103 (2019)

Spectroscopic analysis of keratin endogenous signal for skin multiphoton microscopy

A.-M. Pena, M. Strupler, T. Boulesteix, and M.-C. Schanne-Klein
Opt. Express 13(16) 6268-6274 (2005)

Recent applications of FT-IR spectroscopy to polymer systems

J. L. Koenig and M. K. Antoon
Appl. Opt. 17(9) 1374-1385 (1978)

Quantitative Fourier transform IR photoacoustic spectroscopy of condensed phases

Y. C. Teng and B. S. H. Royce
Appl. Opt. 21(1) 77-80 (1982)