Gas-phase action spectroscopy of protoporphyrin IX (PP) and zinc-PP anions from 210 nm to 720 nm

Action spectra of isolated gas-phase protoporphyrin IX (PP) and zinc-PP anions are presented here. Such spectra are valuable for protein biospectroscopy as absorption by proteins is often determined by the chromophores microenvironment which is often vacuum-like in the case of hydrophobic pockets. Ions were generated using electrospray ionisation, photoexcited in an electrostatic storage ring and their decay monitored in time. Action spectra were obtained by analyzing the time spectra at each wavelength.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (213 K)Download as PowerPoint slideHighlights► Action spectra of gas-phase protoporphyrin IX (PP) and zinc-PP anions were measured. ► The action spectra of isolated chromophores are valuable for protein biospectroscopy. ► Time spectra at each wavelength were measured. ► Absorption bands were measured at 299 nm, 386 nm, 499 nm, 535 nm and 581 nm for PP−. ► Absorption bands were measured at 401 nm, 542 nm and 576 nm for ZnPP−.