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Luminescence Spectroscopy of Rhodamine Homodimer Dications in Vacuo Reveals Strong Dye‐Dye Interactions
Author(s) -
Kjær Christina,
Lissau Henriette,
Gravesen Salinas Nina Katharina,
Østergaard Madsen Andreas,
Stockett Mark H.,
Storm Freja E.,
Holm Hansen Thomas,
Andersen Jens Ulrik,
Laursen Bo W.,
Mikkelsen Kurt V.,
Brøndsted Nielsen Mogens,
Brøndsted Nielsen Steen
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201800933
Subject(s) - luminescence , photochemistry , chemistry , excited state , ground state , rhodamine , fluorescence , spectroscopy , chemical physics , ionic bonding , monomer , ion , dipole , analytical chemistry (journal) , atomic physics , materials science , physics , optoelectronics , organic chemistry , polymer , quantum mechanics
Abstract Being alone or together makes a difference for the photophysics of dyes but for ionic dyes it is difficult to quantify the interactions due to solvent screening and nearby counter ions. Gas‐phase luminescence experiments are desirable and now possible based on recent developments in mass spectrometry. Here we present results on tailor‐made rhodamine homodimers where two dye cations are separated by methylene linkers, (CH 2 ) n . In solution the fluorescence is almost identical to that from the monomer whereas the emission from bare cation dimers redshifts with decreasing n . In the absence of screening, the electric field from the charge on one dye is strong enough to polarize the other dye, both in the ground state and in the excited state. An electrostatic model based on symmetric dye responses (equal induced‐dipole moments in ground state) captures the underlying physics and demonstrates interaction even at large distances. Our results have possible implications for gas‐phase Förster Resonance Energy Transfer.