Enhancing Gas Detection Limits in Raman Spectroscopy: Implications for the Exploration of Mars and Other Planetary Surfaces

Raman spectroscopy is a powerful technique capable of characterising the composition and structure of mineral targets. Its high specificity can also be used to measure gas composition and detect minor components in an atmosphere, including methane and other hydrocarbons. Furthermore, some major atmospheric components are diatomic symmetric molecules such as nitrogen and oxygen, which are non- absorptive and therefore cannot be observed by IR spectroscopy. Raman is an alternative for these cases that provides a thorough picture of the planetary atmospheric composition. However, the lower density of gases compared to mineral or liquid solutions results in a weaker Raman response, making it difficult to apply the technique in this case. In this study, we present a method to improve the efficiency of this process by utilizing hollow core fibers, increasing the interrogated volume of gas and guiding the scattered light to the collection device. This greatly improves the signal to noise ratio of the gas molecule peaks, enabling the measurement of gases at trace gas concentrations and leading towards the ability to detect volatile compounds.