Tag Archives: emission

Self-Absorption in Flame Emission Spectroscopy

Flame emission is subject to the same types of chemical interferences as atomic absorption. These interferences are minimized by adjusting the flame’s composition and adding protecting agents, releasing agents, or ionization suppressors. An additional chemical interference results from self-absorption. Because … Continue reading

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Background Corrections in Emission Spectroscopy

The most important spectral interference in emission spectroscopy is broad, background emission from the flame or plasma, and emission bands from molecular species. This background emission is particularly severe for flames because the temperature is insufficient to break down refractory … Continue reading

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Inductively Coupled Plasma Torch

The illustration below provides a schematic diagram of an inductively coupled plasma source (ICP), which consists of three concentric quartz tubes surrounded at the top by a radio-frequency induction coil. The sample is mixed with a stream of Ar using … Continue reading

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Fluorescence Emission Spectrum for Tyrosine

A photoluminescence spectrum is recorded by measuring emission intensity  as a function of either the excitation wavelength or the emission wavelength. An excitation spectrum is obtained by monitoring emission at a fixed wavelength while varying the excitation wavelength. When corrected … Continue reading

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Pathways for Deactivating an Excited State Without Emission

Shown here is an illustration of the energy level diagram for a molecule exhibiting pathways for the deactivation of an excited state: vr is vibrational relaxation; ic is internal conversion; ec is external conversion; and isc is an intersystem crossing. … Continue reading

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Singlet and Triplet States

Photoluminescence is divided into two categories: fluorescence and phosphorescence. A pair of electrons occupying the same electronic ground state have opposite spins and are said to be in a singlet spin state; see (a) in the illustration below. When an … Continue reading

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Continuous and Line Sources

A source of electromagnetic radiation must provide an output that is both intense and stable. Sources of electromagnetic radiation are classified as either continuum or line sources. A continuum source emits radiation over a broad range of wavelengths, with a … Continue reading

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Absorbance and Emission Spectroscopy

The illustration here is a simplified energy diagram showing the absorption and emission of a photon by an atom or a molecule. When a photon of energy hν strikes the atom or molecule, absorption may occur if the difference in energy, … Continue reading

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