This study focuses on the application of Microfluidic Modulation Spectroscopy (MMS) to identify and analyze the signature absorption peaks of RNA bases—adenine (A), guanine (G), cytosine (C), and uracil (U). By utilizing the unique vibrational modes corresponding to specific functional groups within these bases, MMS facilitates a detailed analysis of molecular interactions of these RNA building blocks. The signature peaks, derived from the vibrational responses of C-H, N-H, and C=O bonds, provide insights into the base-specific electronic environments and how these are influenced by molecular interactions such as RNA base pairing and stacking. This study not only builds the foundation of the spectral characteristics of each RNA base but also explores the implications of spectral variations for understanding the structural and functional aspects of RNAs.