(2)

The presence of water in lunar materials can significantly impact the evolution of lunar geology and environment, as well as provide necessary conditions for the utilization of lunar resources. However, due to the limitations of lunar remote sensing methods, it is challenging to obtain direct evidence of water or determine its form of occurrence. Laser Raman spectroscopy, on the other hand, can provide valuable information on the type, distribution, and content of water in lunar materials without the need for illumination, sample pretreatment, or destructive measures. In this study, we utilized Raman spectroscopy to detect and quantify the water-containing characteristics of typical lunar rocks and minerals, including adsorbed water, ice, crystalline water, and hydroxyl-structured water. First, we used a 532 nm laser micro-Raman spectroscopy to identify and analyze the water-containing signals of various forms of water in lunar soil simulants. We then examined and analyzed the detection limits of adsorbed water, crystalline water, and hydroxyl- structured water in these simulants, as well as the relationship between their content and signal intensity. Finally, we employed linear regression (LR), ridge regression (RR), and partial least squares regression (PLSR) to quantitatively analyze the contents of these three forms of water in the lunar soil simulants. Our results demonstrate that the characteristic spectral peaks of the four forms of water in the lunar soil simulants can be clearly identified, with peak distribution regions located at 100-1 700 cm(-1) and 2 600-3 900 cm(-1) for the lunar soil components and water bodies, respectively. The spectral peaks of water are a combination of broad envelope peaks of hydrogen-bonded OH and sharp peaks of non- hydrogen-bonded OH stretching vibrations in varying proportions. The detection limits for adsorbed water, crystalline water (MgSO47H(2)O), and hydroxyl water (Al2Si2O5(OH)(4)) in the lunar soil simulants are 1.3 wt%, 0. 8 wt%, and 0. 3 wt%, respectively. There is a linear relationship between the intensity of water-containing peaks and the water content in the lunar soil simulants, with root mean square errors of 1. 75 wt%, 1. 16 wt%, and 1. 19 wt% obtained through LR, RR, and PLSR.

来源平台：JOURNAL OF INFRARED AND MILLIMETER WAVES