Since the mathematical foundations of photothermal effects in condensed phase materials were established in the middle 1970s, new photothermal methodologies have emerged based on the detection of heat generated from the absorption and non-radiative conversion of modulated radiation. Among them, photopyroelectric techniques have become very popular and widely used for a variety of studies ranging from calorimetry (photothermal calorimetry), phase transitions and the measurement of thermophysical (thermal diffusivity, effusivity and conductivity) and optical properties (photopyroelectric spectroscopy). More recently photopyroelectric detection has been used for the direct quantification of the optical absorption coefficient of condensed phase materials and has demonstrated its potential for quantitative analysis. In this work, a survey of various applications of photopyroelectric detection for the analysis of fluids and liquid mixtures is presented with special focus on theoretical and experimental progress in quantitative analytical measurements as new developments in this field.

Photopyroelectric Spectroscopy of Pure Fluids and Liquid Mixtures: Foundations and State-of-the-Art Applications

Photoacoustic Spectroscopy (PAS) has been used extensively in recent years with conventional microphones and piezoelectric detectors as signal transducers The commonest piezoelectric transducers are usually made out of piezoelectric ceramic (eg, lead zirconate titanate, PZT [1 – 3]) These ceramics exhibit a much higher frequency response than microphone transducers, and thus they became dominant in photoacoustic applications where fast transducer response is required, such as pulsed laser PAS [4] Very recently Tam and Coufal [5] and Coufal [6] used polyvinylidene difluoride (PVDF) thin film piezoelectric transducers for pulsed and modulated photoacoustics These films have distinct advantages over PZT transducers, the most important of which being their much higher, essentially flat frequency response between DC and tens of MHz [7] In addition to piezoelectric behaviour, PVDF thin films (Pennwalt KYNAR™) exhibit strong pyroelectric properties [8] and, therefore, they can be used as detectors of thermal radiation Coufal [6] utilized the pyroelectric character of 9 ym thin PVDF films to obtain pulsed and low modulation frequency spectra of Nd2O3 doped poly(methyl methacrylate) films

Experimental and Theoretical Aspects of Frequency-Domain Photopyroelectric Spectroscopy of Condensed Phases (PPES), a New, Simple and Powerful Spectroscopic Technique

John F. Zuccon

Papers

Experimental and Theoretical Aspects of Frequency-Domain Photopyroelectric Spectroscopy of Condensed Phases (PPES), a New, Simple and Powerful Spectroscopic Technique