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Revolution in high-altitude detection: How to use photoacoustic spectroscopy to measure nitrogen oxides in the stratosphere?
In the 1960s, scientists first explored how to use photoacoustic spectroscopy to precisely measure gas concentrations high in the atmosphere, a unique technique that has evolved into a key tool for tracking nitrogen oxides in the atmosphere. As time goes by and technology advances, photoacoustic spectroscopy not only provides accurate data to the scientific community, but also plays an indispensable role in the study of air pollution and climate change.
Photoacoustic spectroscopy is a method of measuring the effects of absorbed electromagnetic energy on matter, using sound to detect it.
The origins of photoacoustic spectroscopy date back to 1880, when Alexander Graham Bell discovered that thin sheets of light made sounds when they were rapidly illuminated by sunlight and interrupted. With subsequent experiments, scientists learned that not only visible light, but also infrared and ultraviolet light can cause sound. This discovery eventually laid the foundation for future high-altitude detection.
Today, modern photoacoustic detectors have undergone a series of improvements based on Bell's technology. These improvements not only increase the sensitivity of the measurement, but also make photoacoustic spectroscopy an effective tool to support stratospheric gas monitoring. Traditional sunlight is replaced by modern powerful lasers, which not only increase the light intensity but also further enhance the generated sound effects. This technique, called laser photoacoustic spectroscopy (LPAS), plays a key role in the detection of gases such as nitrogen oxides.
Using laser photoacoustic spectroscopy, scientists can measure gas concentrations down to a few parts per billion.
For indoor measurements, these new technologies also make some changes, such as replacing the ears with sensitive microphones and using lock-in amplifiers to further amplify the signal, so that the acquired audio can be detected more accurately. The wrapping of the cylindrical gas sample also helps to amplify the sound signal by adjusting the modulation frequency. The integration of these technologies further improves the sensitivity of photoacoustic spectroscopy. In order to achieve better results in detection.
In the early 1970s, scientist Battelle and his colleagues successfully used this technology to measure the changes in nitric oxide at an altitude of 28 kilometers. These data provide a basis for understanding how human-made nitrogen oxides exacerbate the problem of ozone layer depletion. Important reference. These early studies provided a theoretical basis for the subsequent formulation of environmental protection policies.Photoacoustic spectroscopy plays an important role in the evaluation and detection of various types of samples.
Photoacoustic spectroscopy has applications in many fields. In biological sample testing, researchers are able to directly assess the chemical composition of the sample without the need for destruction or chemical treatment. This information is particularly important for studying chemical interactions in marine life or bones, and could also be useful for examining the internal structure of bones in people with osteoporosis.
At the same time, scientists are also constantly exploring new solutions for low-cost applications, planning to integrate photoacoustic spectroscopy technology into the production process to reduce costs and increase user exposure. Over the past two decades, many low-cost instruments have become available that can be used to detect leaks or control carbon dioxide concentrations. Their technical foundations rely primarily on low-cost heat sources, miniaturized designs, and electronic analog devices.
In the future, photoacoustic spectroscopy may realize fully integrated micromechanical instruments and increase its application scenarios.
Photoacoustic spectroscopy also shows potential in the military, especially in detecting toxic chemical agents. Due to its high sensitivity, this technology is effective in identifying trace amounts of chemicals associated with chemical attacks. In addition, the application scope of LPAS sensors covers not only industry, but also fields such as security and medicine, such as breath analysis, which further expands the application prospects of photoacoustic spectroscopy technology.
With continuous technological innovation and its expansion in different fields, photoacoustic spectroscopy will play an increasingly important role in future environmental monitoring and biomedical applications. At the same time, with the advancement of experimental technology, will we witness more new discoveries about environmental protection in the future?
