Fluorescence Spectroscopy

Fluorescence spectroscopy refers to a technique that measures the emission of light from a fluorophore or optical material. Fluorophores absorb light, and then quickly re-emits this energy as a lower energy photon. This is known as fluorescence.

However, fluorescence spectroscopy can also be used as a catch all term for optical spectroscopy measurements used to investigate a materials internal structure, including transmission and absorption measurements. In biological applications, it also refers to techniques such as flow cytometry or fluorescence imaging. This technique can be used to probe many types of materials including organic, optoelectronic, semiconductor, and organic matter materials.

Spectrofluorometers can accurately and precisely measure both fluorescence and absorbance. To measure these as accurately as possible, spectrofluorometers use monochromators to split broadband light into its component wavelengths. In combination with an adjustable slit, monochromators can isolate individual wavelengths of light. In a spectrofluorometer, this light is directed towards a single pixel detector, where intensity is measured. Spectrofluorometers allows users to conduct different spectroscopy measurements with just one instrument, including fluorescence spectroscopy.

Jump to: Browse equipment | Fluorescence Spectroscopy Measurements | Resources and support

Fluorescence Spectroscopy Equipment

Sort by:

Monochromator

Price $3,750

LED Light Source

Price $525

Adjustable Slit

Price $375

Fluorescence Spectroscopy Measurements

Fluorescence

Fluorescence is the rapid re-emission of light by a substance after it absorbs photons. Materials that exhibit this behavior are called fluorophores, and these materials are extremely useful. Either their radiative properties are used directly for optoelectronic devices, or their fluorescent properties can serve as markers, to observe or monitor non-optical systems.

Fluorescence is characterized by three key stages: absorption, where an electron is excited to a higher energy state; vibrational relaxation, where the electron loses some energy through heat; and finally, fluorescence, where the electron returns to its ground state by emitting a photon. A fluorescence spectrum can be measured with a spectrofluorometer.

Fluorescence measurements have a wide range of applications, including material analysis in organic light-emitting diodes (OLEDs), solar cells, and various biological and chemical analyses.

Absorbance Spectroscopy

Absorbance spectroscopy quantifies how much incident light a substance absorbs. The amount of light absorbed is directly related to the concentration of the substance and its intrinsic properties. Absorbance spectroscopy is often used alongside fluorescence spectroscopy and is a fundamental tool for material characterization and analysis.

Most spectrometers and spectrophotometers are capable of measuring absorbance spectra. However, CCD spectrometers typically have lower resolution and accuracy, making them suitable for quick, qualitative measurements. For more rigorous absorbance measurements, spectrophotometers or spectrofluorometers offer higher resolution and sensitivity which is critical for precise quantitative analysis.

Excitation and Emission Spectra

Within fluorescence spectroscopy, there are two methods for measuring a material's optical properties. An emission spectrum is a measurement of how the fluorescence intensity changes across different wavelengths, given a fixed excitation signal. In these measurements, the excitation wavelength is constant while a scanning monochromator scans across the spectrum, measuring different emitted wavelengths.

An excitation spectrum is obtained by fixing the emission wavelength (i.e. the emitted intensity is measured only at one wavelength) while varying the excitation wavelength. This measurement reveals the wavelengths that most effectively stimulate fluorescence.

It's important to distinguish an excitation spectrum from an absorbance spectrum, even though they often look similar. Absorbance is measured using transmitted light—that is, the intensity of light passing through a sample at various wavelengths. While simpler systems like a USB spectrometer can perform this, an excitation measurement requires a dedicated spectrofluorometer, which measures a fluorescent signal instead of transmitted light. The spectra often correlate because a substance is most likely to fluoresce strongly at the wavelengths where it absorbs light most strongly.

Resources and Support

Fluorescence Spectroscopy: Theory, Instrumentation & Uses

Fluorescence spectroscopy can be used to measure a broad range of samples including organic materials, semiconductor devices, optoelectronic materials and biological samples.