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In the great majority of cases, the design of resonant photoacoustic cells is based on the use of resonators excited at the frequencies of their main resonances. This work presents a solution in which the use of a multi-cavity structure with the appropriate selection of the mechanical parameters of the cavities and the interconnecting ducts allows for the shaping of the frequency response of the cell. Such solutions may be particularly useful when the purpose of the designed cells is operation at multiple frequencies, e.g., in applications with the simultaneous detection of multiple gaseous compounds. The concept is tested with cells made using 3D printing technology. The measured frequency responses of the tested cells show very good agreement with the simulation results. This allows for an approach in which the development of a cell with the desired frequency response can be initially based on modeling, without the need for the time-consuming and expensive process of manufacturing and measuring numerous modifications of the cell. [ABSTRACT FROM AUTHOR]

Photoacoustic spectroscopy (PAS) can be utilized as an ultrasensitive gas detection method. The basic principles of gas detection using PAS are discussed in this paper. First, the basic instrumentation for a PAS gas detection system is introduced focusing on the photoacoustic cell. The discussion includes non-resonant photoacoustic cells and the different types of resonant photoacoustic cells, including the longitudinal photoacoustic cell, the Helmholtz photoacoustic cell, the T-type photoacoustic cell, and the high-frequency resonant photoacoustic cell. The basic working principles of each of these, cells as well as the advantages and disadvantages of photoacoustic cells are discussed, and the development of newer types of photoacoustic cells in recent years is outlined in detail. This review provides detailed reference information and guidance for interested researchers who would like to design and build advanced photoacoustic cells for gas detection. Graphical abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols play a pivotal role in the earth-atmospheric system. Analyzing their optical properties, specifically absorption and scattering coefficients, is essential for comprehending the impact of aerosols on climate. When different optical properties of aerosols are individually measured using multiple devices, cumulative errors in the detection results inevitably occur. To address this challenge, based on photoacoustic spectroscopy (PAS) and integrating sphere (IS) scattering enhancement, a compact gas cell (PASIS-Cell) was developed. The PASIS-Cell comprises a dual-T-type photoacoustic cell (DTPAC) and an IS. IS is coupled with DTPAC through a transparent quartz tube, thereby enhancing the scattering signal without compromising the acoustic characteristics of DTPAC. Concurrently, DTPAC can realize high-performance photoacoustic detection of absorption signal. Experimental results demonstrate that PASIS-Cell can simultaneously invert atmospheric aerosol absorption and scattering coefficients, with a minimum detection limit of less than 1 Mm−1, showcasing its potential in the analysis of aerosol optical properties.

In photoacoustic spectroscopy, the photoacoustic cell plays the role of amplifying the photoacoustic signal, and the optimization of its parameters affects the sensitivity and dimensions of the whole system. However, none of the current optimization studies of photoacoustic cells have considered in depth the influence of beam waist radius, which limits the reduction of the size of photoacoustic cells. In this paper, based on the theory of photoacoustic spectroscopy, considering the inhomogeneity of the spatial distribution of the Gaussian beam energy and neglecting the loss of the beam in the acoustic resonator, a theoretical model of the effect of the beam waist radius on the cell constant of the first-order longitudinal resonant frequency is established. Six photoacoustic cells with different resonator radii were designed and measured for acetylene at five different beam waist radii. The relationship among beam waist radius, radius of acoustic resonator and cell constants shows that choosing a radius of resonator that matches the waist radius results in a more sensitive and smaller photoacoustic cell. The study provides a reference for the design of miniaturized photoacoustic cells with high sensitivity, thus promising to further improve the miniaturization of photoacoustic spectroscopy systems for more application scenarios. • A model of the effect of waist radius on the cell constant is established. • Choose a radius of resonator that matches the waist radius. • Considering the waist radius makes the photoacoustic cell smaller and more sensitive. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols play a pivotal role in the earth-atmospheric system. Analyzing their optical properties, specifically absorption and scattering coefficients, is essential for comprehending the impact of aerosols on climate. When different optical properties of aerosols are individually measured using multiple devices, cumulative errors in the detection results inevitably occur. To address this challenge, based on photoacoustic spectroscopy (PAS) and integrating sphere (IS) scattering enhancement, a compact gas cell (PASIS-Cell) was developed. The PASIS-Cell comprises a dual-T-type photoacoustic cell (DTPAC) and an IS. IS is coupled with DTPAC through a transparent quartz tube, thereby enhancing the scattering signal without compromising the acoustic characteristics of DTPAC. Concurrently, DTPAC can realize high-performance photoacoustic detection of absorption signal. Experimental results demonstrate that PASIS-Cell can simultaneously invert atmospheric aerosol absorption and scattering coefficients, with a minimum detection limit of less than 1 Mm -1 , showcasing its potential in the analysis of aerosol optical properties., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)