Application of photoacoustics to biology: some specific systems and methods

1986 ◽  
Vol 64 (9) ◽  
pp. 1132-1135 ◽  
Author(s):  
D. Balasubramanian ◽  
Ch. Mohan Rao
Keyword(s):  
Fourier Transform ◽  
Photoacoustic Spectroscopy ◽  
Biological Systems ◽  
Depth Profiling ◽  
Photoacoustic Signal ◽  
Mirage Effect ◽  
Photoacoustic Spectra ◽  
New Methods

A recent review of applications of photoacoustic spectroscopy to biological systems is presented. Examples of chromophore studies by photoacoustic spectroscopy show that a good correlation is possible between their presence or interactions and the photoacoustic spectra. Emphasis is placed on new interpretations of the photoacoustic signal as well as new methods such as depth profiling, the mirage effect, and Fourier-transform photoacoustic spectroscopy.

Phase-Resolved Depth Profiling of Thin-Layered Plasma Polymer Films by Step-Scan Fourier Transform Infrared Photoacoustic Spectroscopy

1997 ◽  
Vol 51 (8) ◽  
pp. 1238-1244 ◽  
Author(s):  
Eric Y. Jiang ◽  
Richard A. Palmer ◽  
Nancy E. Barr ◽  
Nicholas Morosoff
Keyword(s):  
Fourier Transform ◽  
Photoacoustic Spectroscopy ◽  
Depth Profiling ◽  
Photoacoustic Signal ◽  
Phase Spectrum ◽  
Plasma Polymer ◽  
Plasma Polymers ◽  
Infrared Photoacoustic Spectroscopy ◽  
Direct Use ◽  
Profiling Analysis

After reviewing the background of step-scan interferometric photoacoustic spectroscopy, this paper describes a step-scan Fourier transform photoacoustic phase-resolved technique and its applications in depth profiling of micrometer -thick layered plasma polymers. In particular, the power of direct use of the photoacoustic phase spectrum in both qualitative and quantitative depth profiling of the layered samples is extensively discussed. The effects of both spatial origin and intensity of a photoacoustic signal on its phase have been explicitly analyzed for both overlapping and distinctive, nonoverlapping, bands of the thin-layered plasma polymer samples. The phase spectrum technique is shown to be a very effective and efficient method of spectral depth profiling analysis.

Fourier-transform photoacoustic spectroscopy: a more complete method for quantitative analysis

1986 ◽  
Vol 64 (9) ◽  
pp. 1081-1085 ◽  
Author(s):  
M. Choquet ◽  
G. Rousset ◽  
L. Bertrand
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
Quantitative Analysis ◽  
Photoacoustic Spectroscopy ◽  
Photoacoustic Signal ◽  
Strong Absorption ◽  
Absorption Bands ◽  
Asbestos Fibers ◽  
Fourier Transform Spectra ◽  
Signal Saturation

Strong absorption bands of photoacoustic Fourier-transform spectra are often truncated relative to weaker bands owing to signal saturation. To correct this problem, we propose processing both the phase and the amplitude information in the photoacoustic signal. Under certain conditions, easily fulfilled in typical experiments, we are able to calculate the absolute absorption spectrum from the photoacoustic data. Experimental results are given for asbestos fibers (chrysotile).

Time-Resolved Impulse Photoacoustic Measurements by Step-Scan FT-IR Spectrometry

1996 ◽  
Vol 50 (7) ◽  
pp. 939-947 ◽  
Author(s):  
Boiana O. Budevska ◽  
Christopher J. Manning
Keyword(s):  
Phase Modulation ◽  
Depth Profiling ◽  
Photoacoustic Signal ◽  
Time Dependent ◽  
Solid Samples ◽  
Time Resolved ◽  
Ir Spectrometry ◽  
Photoacoustic Spectra ◽  
Interferometric Phase ◽  
Ft Ir

An impulse/response approach for measuring photoacoustic spectra is described. Instead of the usual modulation from either a chopper or an interferometric phase modulation, a radiation pulse is used to generate the photoacoustic (PA) signal at each step of a step-scan FT-IR spectrometer. The signal from the PA cell is recorded as a time-resolved sequence. The time-dependent photoacoustic signal reveals depth-profiling information for solid samples. Examples of time-resolved impulse photoacoustic spectra (TRIPAS) of gas and solid samples are presented.

Advantages of Phase Analysis in Fourier Transform Infrared Photoacoustic Spectroscopy

1988 ◽  
Vol 42 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Lionel Bertrand
Keyword(s):  
Fourier Transform ◽  
Phase Analysis ◽  
Thermal Diffusion ◽  
Photoacoustic Spectroscopy ◽  
Diffusion Length ◽  
Fourier Transform Infrared ◽  
Photoacoustic Signal ◽  
Thermal Diffusion Length ◽  
Phase Saturation ◽  
Infrared Photoacoustic Spectroscopy

Fourier transform infrared photoacoustic spectroscopy is greatly improved by the simultaneous measurement of the photoacoustic signal amplitude and phase. Saturation effects, sample dilation, and optical scattering, even in heterogeneous samples, can be easily corrected to give the absorption coefficient real value. Quantitative analyses without any special sample preparation or special photoacoustic cell are now possible. Moreover, the phase of the photoacoustic signal permits depth localization of the absorbing species within the thermal diffusion length. Surface analyses are thus possible that have a depth resolution at least one order of magnitude higher than that obtained by changing the thermal diffusion length. In this paper we illustrate the advantages of phase analysis in Fourier transform infrared photoacoustic spectroscopy with the detection of sorbed water in polyethylene.

Analysis of Cheese Using Step-Scan Fourier Transform Infrared Photoacoustic Spectroscopy

2000 ◽  
Vol 54 (4) ◽  
pp. 595-600 ◽  
Author(s):  
Joseph Irudayaraj ◽  
Hong Yang
Keyword(s):  
Signal Processing ◽  
Fourier Transform ◽  
Photoacoustic Spectroscopy ◽  
Depth Profiling ◽  
Cheddar Cheese ◽  
Digital Signal ◽  
Fourier Transform Infrared ◽  
Intact Sample ◽  
Ft Ir ◽  
Infrared Photoacoustic Spectroscopy

The potential of Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) for examination of food and the package was demonstrated. Full-fat cheddar cheese slices wrapped in polymer package were chosen as the food sample for analysis. Photoacoustic spectroscopy (PAS) in conjunction with the step-scan and digital signal processing (DSP) function was used to perform depth-profiling studies of the intact sample and package. Well-separated PAS bands of fat and protein were obtained in the spectra of cheddar cheese samples with minimum sample preparation. Cheese samples were kept in a dessicator overnight to minimize the effect of moisture on the PAS spectra. Depth profiling study of the cheese polymer package indicated that there is a diffusion of cheese components into the package during storage.

Sign in / Sign up

Export Citation Format

Share Document