Mikhaylov, Alexander E.Reguardati, Sophie dePahapill, JuriCallis, Patrik R.Kohler, BernRebane, Aleksander2018-09-272018-09-272018-01Mikhaylov, Alexander, Sophie de Reguardati, Juri Pahapill, Patrik R. Callis, Bern Kohler, and Aleksander Rebane. "Two-photon absorption spectra of fluorescent isomorphic DNA base analogs." Biomedical Optics Express 9, no. 2 (January 2018): 447-452. DOI:10.1364/BOE.9.000447.2156-7085https://scholarworks.montana.edu/handle/1/14878Fluorescent DNA base analogs and intrinsic fluorophores are gaining importance for multiphoton microscopy and imaging, however, their quantitative nonlinear excitation properties have been poorly documented. Here we present the two-photon absorption (2PA) spectra of 2-aminopurine (2AP), 7-methyl guanosine (7MG), isoxanthopterin (IXP), 6-methyl isoxanthopterin (6MI), as well as L-tryptophan (L-trp) and 3-methylindole (3MI) in aqueous solution and some organic solvents measured in the wavelength range 550 - 810 nm using femtosecond two-photon excited fluorescence (2PEF) and nonlinear transmission (NLT) methods. The peak 2PA cross section values range from 0.1 GM (1 GM = 10-50 cm4 s photon-1) for 2AP to 2.0 GM for IXP and 7MG. Assuming typical excitation conditions for a scanning 2PEF microscope, we estimate a maximum image frame rate of ~175 frames per second (FPS).enCC BY, This license lets you distribute, remix, tweak, and build upon this work, even commercially, as long as you credit the original creator for this work. This is the most accommodating of licenses offered. Recommended for maximum dissemination and use of licensed materials.http://creativecommons.org/licenses/by/4.0/legalcodeArticle