Temperature Effects on Inorganic Sensors

Design and Applications of Highly Luminescent Transition Metal Complexes 

Although not plotted, there is a parallel correlation between absolute luminescence efficiency, 0, (photons emitted per photon absorbed) and observed lifetime. 

There are possible advantages of the temperature dependence of excited state lifetimes. The dependence can be used for luminescence-based temperature sensors, which is an area of considerable interest. Clearly, with a suitable AE, complexes that give significant lifetime changes in a wide range of possible temperatures can be designed. We discuss this issue elsewhere.(16) 

Specific examples are now used to demonstrate these concepts. First, consider the group Ru(bpy)j2+ (luminescent), Os(bpy)32+ (slightly luminescent), and Fe(bpy)32+ (nonluminescent) (Table4.1). For Fe(bpy)32+, despite an exhaustive search no emission has ever been detected even at 77K we routinely use it as a nonemissive solution filter. All three iso structural eft systems are in the same oxidation state with the same electronic configuration (ft6). The Fe(II) complex has an intense MLCT band at 510 nm, and the Ru(II) complex at 450 nm the Os(II) complex has intense MLCT bands that stretch out to 700 nm. The n-n transitions are all quite similar in all three complexes with intense absorptions around 290 nm and ligand triplet states at 450 nm (inferred from the free ligand and other emissive complexes and the insensitivity of these states to coordination to different metals). 

which shows the positions of their lowest d-d, MLCT, and n-n triplet states. The ligands are the same, but A increases dramatically on going from iron (Fe) to ruthenium (Ru) to osmium (Os). Thus, Ihc Vi d state energies rise pronouncedly on going from Fe to Ru to Os. Further, the ease of oxidation of the metal to the +3 oxidation state is 

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