The absorption and fluorescence spectrum of heptamethine dyes are in the near infrared region and vary largely on the solvent and concentration. IR-808 absorbs mainly between 775 nm and 796 nm and emits fluorescence between 808 nm and 827 nm with a large red shift as expected in the serum sample. These absorption rates are important for their medical applications due to the image capturing capabilities. Dyes with good pharmacokinetics and fluorescence above 680 nm are considered viable in biomedical imaging due to their significant tissue penetration and imaging signature relative to background frequencies.
