As outlined in the Methodology Section, we tested both the joint training of Spectro with j-IRvis, and Spectro with fixed IR and NMR embeddings. To quantify the model's accuracy, we employed two metrics, Tanimoto Similarity (TS) and the Number of Wrong Tokens (NWT), defined as, NWT(y, ŷ) = M i 1 -δ(y i = ŷi ) where y and ŷ represent the tokens of the predicted and target molecule respectively, and M is the total number of tokens, M = 45. For all molecules, the TS was computed using RDKit with 2, 048 bits.