• Top library match: Diethyl carbonate #81980

• The library match quality is extremely weak: all reported top candidates have 0.000 similarity, S-O the named top hit cannot be treated as a reliable identification.
• The Top-15 candidates are chemically mixed, including carbonate, benzoate esters, fluorinated species, aldehydes, and N-containing compounds, which limits confidence in any narrow assignment.
• No related-literature evidence was recovered to narrow the structure beyond a broad oxygenated carbonyl direction.
• The present peak list supports functional groups more strongly than a unique molecule.
• It remains uncertain whether the carbonyl-containing material is a simple aliphatic ester, a carbonate, or an aromatic ester.
• The lower-frequency bands do not securely distinguish between non-aromatic and aromatic ester subclasses in the absence of stronger corroborating features.

Recommended next steps: Reacquire the FTIR spectrum with full baseline-corrected intensity data and a wider interpretive review of the 1800-650 cm-1 region to better resolve the carbonyl and C-O pattern. Check specifically for ester versus carbonate differentiation by examining the exact shape and relative intensity of the 1274, 1125, and 1076 cm-1 bands. Inspect the 3100-3000 cm-1 and 1600-1500 cm-1 regions for aromatic C-H and ring bands to test whether an aromatic benzoate-type ester is present. If the sample is liquid or extractable, confirm by GC-MS or LC-MS to distinguish Diethyl carbonate from other low-molecular-weight esters or carbonate-containing compounds.