Chapters 12 Section 12 6 Molecular Luminescence Spectrometry

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Chapters 12 (Section 12 -6) Molecular Luminescence Spectrometry

Chapters 12 (Section 12 -6) Molecular Luminescence Spectrometry

Singlet triplet excited states Ground singlet state Excited singlet state Excired triplet state

Singlet triplet excited states Ground singlet state Excited singlet state Excired triplet state

Triplet excitef state Singlet excited state S 1 Intersystem crossing Vibrational relaxation Intersystem crossing

Triplet excitef state Singlet excited state S 1 Intersystem crossing Vibrational relaxation Intersystem crossing S 2 Absorption T 1 Fluorescence Internal and external conversion Phosphorescence Vibrational relaxation S 0 Ground state Partial energy level diagram for photoluminescent system

Deactivation Processes • • • Vibrational relaxation Internal conversion External conversion Intersystam crossing Phosphorescence

Deactivation Processes • • • Vibrational relaxation Internal conversion External conversion Intersystam crossing Phosphorescence

S 1 Absorption S 0 Ground state Vibrational relaxation

S 1 Absorption S 0 Ground state Vibrational relaxation

Internal conversion Vibrational relaxation S 1 S 2 Absorption Vibrational relaxation Absorption Vibrational Fluorescence

Internal conversion Vibrational relaxation S 1 S 2 Absorption Vibrational relaxation Absorption Vibrational Fluorescence Fluoresence relaxation S 0

Predissociation Dissociation

Predissociation Dissociation

Internal conversion Intersystem crossing Vibrational relaxation S 1 S 2 T 1 Vibrational relaxation

Internal conversion Intersystem crossing Vibrational relaxation S 1 S 2 T 1 Vibrational relaxation Absorption S 0 Vibrational Phosphorescence relaxation

Relative intensity Excitation Emission 200 250 300 350 400 450 500 Wavelength nm 550

Relative intensity Excitation Emission 200 250 300 350 400 450 500 Wavelength nm 550 600 Fluorescence excitation and emission spectra for a solution of quinine

Relative intensity 200 Excitation 300 Fluorescence 400 Phosphorescence 500 600

Relative intensity 200 Excitation 300 Fluorescence 400 Phosphorescence 500 600

Excitation filter or monochromator l 1 Beam attenuator Sample l 2 Emission filter or

Excitation filter or monochromator l 1 Beam attenuator Sample l 2 Emission filter or monochromator l 1 Reference photomultiplier l 2 Sample photomultiplier Difference amplifier 345. 6 Readout Components of a fluorometer or spectrofluorometer

300 350 400 Excitation spectrum Emission spectrum 300 350 400 Fluorescence spectra for 1

300 350 400 Excitation spectrum Emission spectrum 300 350 400 Fluorescence spectra for 1 ppm anthracene in alcohol

Sample aperture disk Shutter Primary filter Reference aperture disk Secondary filter Mirror Sample photomultiplier

Sample aperture disk Shutter Primary filter Reference aperture disk Secondary filter Mirror Sample photomultiplier Reference photomultiplier Sample A typical fluorometer

Excitation monochromator Emission monochromator Grating Reference photomultiplier tube Sample photomultiplier tube Absorbance compensating cell

Excitation monochromator Emission monochromator Grating Reference photomultiplier tube Sample photomultiplier tube Absorbance compensating cell Beam splitter Xenon lamp Sample compartment A spectrofluorimeter

From excitation monochromator Dewar flask with liquid nitrogen To emission monochromator Schematic of a

From excitation monochromator Dewar flask with liquid nitrogen To emission monochromator Schematic of a device to alternatively exciting and observing phosphorescence.

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