A Unified Prediction Strategy for Angle-Resolved Polarized Raman Response of Black Phosphorus

Predicting the angle-resolved polarized Raman spectroscopy (ARPRS) response of anisotropic layered materials (ALMs) is the ultimate goal in the field of ARPRS research. So far, multiple physical mechanisms are studied on the representative black phosphorus (BP) to understand the intricate ARPRS response. However, the lack of a complete physical picture of the response modulation has hindered progress in response prediction. Herein, using BP as an example, a unified strategy for predicting the thickness-dependent ARPRS response of ALMs is proposed. Crucially, with only one ARPRS measurement of a bulk ALM of interest, the response of nanoflakes of any thickness can be predicted. This is achieved based on the core concept of intrinsic Raman anisotropy (RA). Integrated experiments, analysis, and calculations reveal that the response of bulk BP is reshaped by the rarely noticed anisotropic absorption effect, which leads to an unique thickness-independent constant modulation. Therefore, the interference-free bulk counterpart of ALMs can serve as an ideal platform for accurately accessing intrinsic RA. This work provides a new paradigm for ARPRS research and paves the way for profound study of intrinsic RA.