Optical detection of zero-field transitions in phosphorescent triplet states

✍ Scribed by J. Schmidt; J.H. Van Der Waals

• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 307 KB
• Volume: 2
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(63)80039-1

✦ Synopsis

Recently several investigators reported opti-aZ detection of ESR transitions in phosphoresent triplet states of various molecules [l-3]. he experiments were done by sweeping the magetic field at fixed microwave frequency. In con-;ast with the normal ESR detection method. the Jsorption of microwave power was detected as change in intensity of the emitted phosphoresmce light.

Hutchison and his school. on the other hand. tve realized the direct observation of zero-field ansitions between the components of the triplet ate of organic molecules [4/. They measured e absorption of microwave power of variable equency by the sampIe, but in order to achieve fficient sensitivity.

they had to resort to molation by a weak magnetic'field.

Clearly. it is promising to combine the two easand study the zero-field transitions with an ttical detection method. Relative to conventionzero-fieId spectroscopy this offers the advan-:e of circ&nventing the difficulties inherent in de-band microwave detection methods. As comred to the above ESR experiments.

the absence an external magnetic field eliminates the anitropy introduced by such a field and the scram-.ng of zero-field sublevels with different modes decay. .In the present, preliminary note we ow the feasibility of such an approach. In our experimental set-up. power from a crowave oscillator is fed into a helix which