TY - JOUR

T1 - Cryogenic Absorption and Emission Spectroscopy of the Oxyluciferin Anion In Vacuo

AU - Langeland, Jeppe

AU - Christensen, Nanna Falk

AU - Vogt, Emil

AU - Kjær, Christina

AU - Lindkvist, Thomas Toft

AU - Nielsen, Steen Brøndsted

AU - Kjaergaard, Henrik G.

PY - 2023

Y1 - 2023

N2 - Bioluminescence from fireflies, click beetles, and railroad worms ranges in color from green-yellow to orange to red. The keto form of oxyluciferin is considered a key emitter species in the proposed mechanisms to account for color variation. To establish the intrinsic photophysics in the absence of a microenvironment, we present experimental and theoretical gas-phase absorption and emission spectra of the 5,5-dimethyloxyluciferin anion (keto form) at room and cryogenic temperatures as well as lifetime measurements based on fluorescence. The theoretical model includes all 75 vibrational modes. The spectral impact of the large number of excited states at elevated temperatures is captured by an effective state distribution. At low temperature, spectral congestion is greatly reduced, and the observed well-resolved vibrational features are assigned to multiple Franck–Condon progressions involving different vibrational modes. An in-plane ∼60 cm–1 scissoring mode is found to be involved in the dominant progressions.

AB - Bioluminescence from fireflies, click beetles, and railroad worms ranges in color from green-yellow to orange to red. The keto form of oxyluciferin is considered a key emitter species in the proposed mechanisms to account for color variation. To establish the intrinsic photophysics in the absence of a microenvironment, we present experimental and theoretical gas-phase absorption and emission spectra of the 5,5-dimethyloxyluciferin anion (keto form) at room and cryogenic temperatures as well as lifetime measurements based on fluorescence. The theoretical model includes all 75 vibrational modes. The spectral impact of the large number of excited states at elevated temperatures is captured by an effective state distribution. At low temperature, spectral congestion is greatly reduced, and the observed well-resolved vibrational features are assigned to multiple Franck–Condon progressions involving different vibrational modes. An in-plane ∼60 cm–1 scissoring mode is found to be involved in the dominant progressions.

U2 - 10.1021/acs.jpclett.3c01206

DO - 10.1021/acs.jpclett.3c01206

M3 - Journal article

C2 - 37345799

VL - 14

SP - 5949

EP - 5954

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

SN - 1948-7185

IS - 25

ER -