Phase References and Cell Effects in Photoacoustic Spectroscopy

Jones, Roger; McClelland, John F.

doi:10.1366/0003702011953487

Cited by 16 publications

(10 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[1][2][3][4][5] The sample under investigation is usually put in a sealed cell (photoacoustic cell) containing air (or other gas), in which one wall is a light window. It has been reported that the position of the sample relative to the window has a considerable effect on the PA signal, due to cell walls and window acting as thermal sinks, [6][7][8] which are dependent on the geometric dimensions of the cell. For PA applications that require a quantitative theoretical treatment, this sample-position-dependence effect must be taken into account.…”

Section: Introductionmentioning

confidence: 99%

Effective Normalization Method for Sample-Position-Dependence Effect in Photoacoustic Spectrometry

Shen

Zhou

et al. 2003

Appl Spectrosc

View full text Add to dashboard Cite

Sample position dependence effect in photoacoustic (PA) spectrometry has been reported by several scientists. This effect must be taken into account in a PA application that requires a quantitative theoretical treatment. In this work, we experimentally investigated PA signal magnitude varying with sample-to-window distance in an MTEC Model 300 Photoacoustic Detector, which has a fixed empty (gas) volume in addition to the sample-to-window-distance-dependent gas volume. An operative method was introduced to obtain the coefficient, which considered the sample-to-window distance and the additional gas volume. With this coefficient, the one-dimensional PA model, developed by Aamodt, Murphy, and Parker, can be employed to quantitatively process PA experimental data, no matter what the sample-to-window distance is. Quantitative measurements of thermal effusivities of two samples were performed to prove this effective normalization method.

show abstract

Section: Introductionmentioning

confidence: 99%

Effective Normalization Method for Sample-Position-Dependence Effect in Photoacoustic Spectrometry

Shen

Zhou

et al. 2003

Appl Spectrosc

View full text Add to dashboard Cite

show abstract

“…The offset in the spectra comes mainly from the different amounts of sample material in the cup between different measurements but also from the different filling heights of the samples in the cup and the different arrangements of the single hairs in the cup. 17,22,23 For a proper data analysis, the offset needs to be corrected. To normalize, every variable (spectral point) was divided by the sum of the value of all variables for the given sample.…”

Section: Resultsmentioning

confidence: 99%

Human Hair in the Identification of Cocaine Abuse with Cantilever-Enhanced Photoacoustic Spectroscopy and Principal Component Analysis

et al. 2013

View full text Add to dashboard Cite

In this study, a novel approach combining different techniques, including Fourier transform infrared (FT-IR) spectroscopy, photoacoustic spectroscopy (PAS) with an interferometric cantilever microphone, and principal component analysis (PCA) along with a proper data preprocessing procedure, have been used in the investigation of hair samples for cocaine abuse. Hair fibers from cocaine-overdose patients have been measured using a simple procedure involving cantilever-enhanced photoacoustic Fourier transform infrared spectroscopy. In addition, a reference group of hair samples from subjects with no cocaine abuse has been measured. We present a first approach to discriminate the cocaine users from the reference group with the photoacoustic method and PCA. With proper data preprocessing methods, the two groups were successfully separated according to their spectra. The results were confirmed with two different classification methods independent of the principal component data analysis.

show abstract

“…Glassy carbon was used as a reference for all measurements because it comes closest to an ideal phase reference. 47 Since the glassy carbon reference absorbs all infrared radiation on its surface, the phase of a sample should lag behind the reference phase over the whole spectral region. A second advantage of using glassy carbon as reference material is the fact that its photoacoustic signal is the same order of magnitude as that of the sample, enabling the reference and sample spectra to be collected at the same amplification.…”

Section: Methodsmentioning

confidence: 99%

Using the Linearization Approach for Synchronizing the Phase of Photoacoustic Reference and Sample Data

Pichler

Sowa

2004

Appl Spectrosc

View full text Add to dashboard Cite

Linearization of photoacoustic spectra is a technique that allows for detection of surface layers and the compensation of saturation effects in photoacoustic spectra by combining amplitude and phase information. The objective of this report is a thorough description of the linearization procedure. The influence of interferogram rotation on the real and imaginary parts of the complex Fourier transformation and on spectral phase angles is shown. The possibility of using the linearization approach to correct for phase differences between reference and sample data is discussed. The method can be used to calculate phase spectra from photoacoustic spectra taken with rapid scan spectrometers.

show abstract

Phase References and Cell Effects in Photoacoustic Spectroscopy

Cited by 16 publications

References 27 publications

Effective Normalization Method for Sample-Position-Dependence Effect in Photoacoustic Spectrometry

Effective Normalization Method for Sample-Position-Dependence Effect in Photoacoustic Spectrometry

Human Hair in the Identification of Cocaine Abuse with Cantilever-Enhanced Photoacoustic Spectroscopy and Principal Component Analysis

Using the Linearization Approach for Synchronizing the Phase of Photoacoustic Reference and Sample Data

Contact Info

Product

Resources

About