Raman spectroscopy of a microbialite sample in Laguna Pozo Bravo

Raman spectroscopy analysis was performed on a microbialite sample from Laguna Pozo Bravo to assess mineralogical variations through both macro- and microscopic observations. Spectra were acquired using backscattering geometry with a LabRam HR Evolution Raman microspectrometer, set to a resolution of 0.4 cm⁻¹ and equipped with a He-Ne laser line (633 nm) at INQUIMAE (UBA-CONICET), Buenos Aires, Argentina. Beam power and acquisition times were optimised for each sample to obtain informative spectra without causing sample alteration. Spectra were recorded using a 50× microscope objective (spatial resolution of approximately 1 μm), with an exposure time of 10-30 s and three accumulations. For band identification, we consulted the RRUFF database (https://rruff.info) and complemented this data with detailed mode assignments from Post, J. <i>et al.</i>

本研究针对采自阿根廷布宜诺斯艾利斯INQUIMAE（UBA-CONICET）拉古纳·波佐·布拉沃（Laguna Pozo Bravo）的微生物岩（microbialite）样品开展拉曼光谱（Raman spectroscopy）分析，通过宏观与微观观测手段评估其矿物学特征变化。光谱数据采用背散射（backscattering）几何构型采集，使用LabRam HR Evolution型拉曼显微光谱仪，设置分辨率为0.4 cm⁻¹，搭配氦氖（He-Ne）激光线（波长633 nm）。针对每个样品优化了激光功率与采集时长，以获取信息丰富的光谱数据且不会造成样品改性。光谱采集采用50×显微镜物镜（空间分辨率约1 μm），曝光时长为10~30 s，累计采集3次。关于谱带指认，本研究参考了RRUFF数据库（https://rruff.info），并辅以Post J.等人提出的详细振动模式归属结果。