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.

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.

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.

Fourier Transform Infrared Photoacoustic Spectroscopy Characterization of Sulfur-Oxygen Species Resulting from the Reaction of SO2 with CaO and CaCO3

1987 ◽  
Vol 41 (1) ◽  
pp. 120-126 ◽  
Author(s):  
Meg A. Martin ◽  
Jeffrey W. Childers ◽  
Richard A. Palmer
Keyword(s):  
Fourier Transform ◽  
Photoacoustic Spectroscopy ◽  
Depth Profiling ◽  
Fourier Transform Infrared ◽  
Product Layer ◽  
Oxygen Species ◽  
Initial Product ◽  
Ft Ir ◽  
Infrared Photoacoustic Spectroscopy

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) has been used to investigate the reaction of SO2, in He with CaO and CaCO3 particles at temperatures between 25 and 900°C. The reaction of SO2 with CaO occurs at 25°C, while the reaction of CaCO3 with SO2 is first evident at 550°C. The initial product of both of these reactions is CaSO3. The CaSO3 then further reacts with SO2 to form CaSO4, CaS2O3, and CaS at higher temperatures. At 900°C and above, the net production of SO4= and S2O3= is decreased because of the decomposition of SO3=. FT-IR/PAS depth-profiling experiments indicate the formation of a reaction-limiting product layer of SO3= and SO4= from the above reactions on the surface of the CaO and CaCO3 particles.

scholarly journals Responses of Leaf Cuticles to Rice Blast: Detection and Identification Using Depth-Profiling Fourier Transform Mid-Infrared Photoacoustic Spectroscopy

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 847-852 ◽  
Author(s):  
Lv Gaoqiang ◽  
Du Changwen ◽  
Ma Fei ◽  
Shen Yazhen ◽  
Zhou Jianmin
Keyword(s):  
Fourier Transform ◽  
Early Detection ◽  
Photoacoustic Spectroscopy ◽  
Rice Blast ◽  
Probabilistic Neural Network ◽  
Depth Profiling ◽  
Rice Leaf ◽  
Leaf Cuticle ◽  
Blast Fungus ◽  
Infrared Photoacoustic Spectroscopy

Cuticle is the first barrier for rice to resist blast fungus on the surface of the leaf. Studies on how the rice leaf cuticle responds to rice blast and attempts to perform early detection of rice blast are limited, and these two issues were explored in this study via depth-profiling Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS). Rice leaves with four different scales of injury (healthy leaves as CK, asymptomatic leaves from mildly diseased seedlings as S1, infected leaves with fewer than five lesions as S2, and infected leaves with more than 10 lesions as S3) were scanned by three moving mirror velocities 0.32, 0.47, and 0.63 cm/s for the depth profiling of the rice leaf surface. The response patterns were acquired via chemometrics to analyze the variations of the chemical group absorptions in the different layers of a sample and in the same layer between different samples. Results showed that the leaf cuticle tended to be thicker and the relative content of fatty alcohols and cutin, unsaturated compounds, and aromatics in the cuticle increased when rice seedlings were infected by blast fungus. Together with the principal component analysis, the probabilistic neural network was applied to identify the samples in early stages (CK and S1), which reached an accuracy of 90% for the samples in the greenhouse and 82% for the samples in the field. Thus, depth-profiling FTIR-PAS was good at analyzing the variation in cuticle layers and showed great potential in the early detection of rice blast or other diseases in different species.

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