imoptosky@gmail.com
Navigation
media

Principles of Fluorescence Emission and Fluorescence Analysis

Fluorescence emission occurs when a substance absorbs light at a specific wavelength and re-emits it at a longer wavelength. Fluorescence analysis leverages this property for sensitive detection and quantification of compounds in various fields, including biology and environmental science.

The basic principles of fluorescence

Fluorescence is a type of radiative transition, where radiation is emitted as a substance relaxes from an excited state to a lower energy state of the same multiplicity. From a microscopic perspective, when molecules are illuminated, they absorb photon energy, causing electrons within the molecules to transition from a lower energy level to a higher one. They then return to the ground state through radiative or non-radiative decay processes, emitting photons in the process, which produces fluorescence or phosphorescence. Fluorescence emission occurs simultaneously with radiation and quickly disappears when the radiation stops. In contrast, phosphorescence involves a delay from the time of radiation absorption to when the light intensity peaks, and the emission persists for a period after radiation ceases.

01 Fluorescence test method

Fluorescence can be categorized into steady-state and transient fluorescence measurements in the time domain. Fluorescence spectroscopy is suitable for analyzing solid powders, crystals, films, and liquids. Depending on the sample type, quartz cuvettes (for liquids) or solid sample holders (for powders or films) are used. Based on steady-state and transient fluorescence, fluorescence spectral analysis can be coupled with microscopy to obtain micro-area analysis results and can adapt to various external experimental conditions to yield fluorescence spectra under different temperatures, pressures, and magnetic fields.

02 Two-dimensional fluorescence spectroscopy

Two-dimensional fluorescence spectroscopy mainly includes fluorescence emission spectra and excitation spectra. The fluorescence emission spectrum is obtained by fixing the incident wavelength to excite the substance and detecting the distribution of fluorescence intensity with respect to emission wavelength. The excitation spectrum is measured by fixing the emission wavelength and detecting fluorescence intensity as a function of different incident wavelengths. Conventional fluorescence analysis techniques primarily perform qualitative and quantitative analysis of inorganic and organic compounds.

03 Synchronous fluorescence spectroscopy

Synchrofluorescence analysis, first proposed by Lloyd, distinguishes itself by methods such as constant (fixed) wavelength, constant energy, variable angle, and constant matrix methods. It leverages the absorption and emission characteristics of compounds, improving the selectivity of spectral analysis. Synchrofluorescence spectroscopy enhances strong bands while minimizing interference from weak bands, effectively eliminating Rayleigh interference and broadening Raman intensity. This technique is well-suited for analyzing multi-component mixtures, finding widespread applications in environmental, pharmaceutical, clinical, and chemical industries.

04 Three-dimensional fluorescence spectrum

Three-dimensional fluorescence spectroscopy is a new technique developed in recent decades. Fluorescence intensity is actually a function of both excitation and emission wavelengths. A three-dimensional fluorescence spectrum describes the relationship between fluorescence intensity and these two variables, providing more comprehensive spectral information than conventional or synchrofluorescence spectroscopies. In a multi-component system's three-dimensional fluorescence spectrum, each component has a distinct absorption and emission spectral region, allowing for the detection of all components in a single scan. This technique serves as a spectral fingerprint method in environmental monitoring, clinical chemistry (distinguishing cancer from non-cancer cells based on fluorescent metabolic products), and bacterial identification, among other applications. It can also be used for monitoring photochemical reactions and qualitative and quantitative analysis of multi-component mixtures.

The fluorescence quantum yield (φf) is another fundamental parameter of fluorescent substances, indicating the ability of a substance to fluoresce, with values ranging from 0 to 1. The yield depends on the chemical structure of the substance and environmental factors (temperature, pH, solvent, etc.). Various methods exist for measuring the quantum yield, typically using a reference method. This involves comparing the integral fluorescence intensity of the test substance and a reference substance with a known quantum yield, both measured under identical excitation conditions. Fluorescence quantum yield measurements provide insights into the optical properties and chemical composition of substances, with applications in materials science, biological science, medicine, optical devices, and energy science.

Comments: 0

No comments

Leave a Reply

Your email address cannot be published. Required fields are marked*

Popular Tags
fast identify liquid reagent on quanitification method How to Controll Drugs and Narcotics by Safity Non-destructive Identification? ATR8000 automatic high-throughput Raman spectrometer ATR8000-first-appeared all-automatic & high throughput portable Raman analyzer OPTOSKY AT SPIE BIOS Expo 2020 fast test fake by raman OPTOSKY is coming to SPIE ATR8000 detect demonstration Thanksgiving! Raman identify starch medicinal accessories ATR3200 Double-Wavelength Raman Spectrometer ATH3010 Rotary-broom hyperspectral camera What is the advantage of 1064nm Raman of Optosky? What is the new choise for Raman characterization f carbon materials? new method for rapid detection of counterfeit drugs handheld raman spectrometer raman spectrometer raman spectrometer diagram optosky Why optosky measures absorbance by modular spectrometer? Handheld Raman spectrometer of optosky optical analysis instrument RMID raman spectrscopy portable Raman analyzer Merry Christmas from optosky How is the Raman spectrometer of optosky used in optical ? New dual wavelength Raman spectrometer for detect small sample in lab. ATR6500 penetrating and long-distance video How many advantagesof Raman ID applied to pharmaceutical industry? 2020 SPIE BIOS And West Photonic Show with Optosky 【Video】Portable Hyperspectral Camera measure ATH60 series Lab Hyperspectral Imaging Cabinet detect Airborne Hyperspectral Imaging Diamond Raman OPTOSKY Is Ready For 2020 live Live What is the advantage of 1064nm Raman spectrometer? NanoBio serise uv-vis Spectrometer UV-Vis Spectrophotometer How to use 1064nm Handheld Raman Spectrometer rapid test narcotics ? Raman spectroscopy Fieldspec Portable NIR Grain Analyzer Handheld RamanSpectrometer fast measure accurate test Measuring Fentanyl full-range spectroradiometers Soil salinization Portable Raman Spectroscopy ,Food Analysis Field Operation Food Safety The Fieldspec Accessory --Contact Probe Hyperspectral remote sensing 5th generation ultra-light ultra-thin small size Pocket Raman Spectrometer Mini Instrument fieldspec Crop yield estimation Hyperspectral remote sensing technology Hand-held Raman Raman Spectrometer Portable or Benchtop Raman Sorting Technology Raman Raman spectrometer Hyperspectral imager Hyperspectral and LiDAR data identify -diamonds-raman- spectrometer Borax ID by Raman Imaging Microscope Ancient Painting Restoration by Confocal Raman Microscope soybean varieties classification Red tides detailed spatial distribution rice leaf blast (RLB) infection raman imaging microscope Ultraviolet (UV) hyperspectral the manufacturing product chain Scientific -Grade Quodriband Raman Microscope Raman Spectrometer for Food Additive Detection Raman Spectrometer For Distinguishing Chinese herbal medicine raman microspectrometer cataracts Experimental Teaching System of Raman Spectrometer chemical research Textile testing Raman technology Raman spectrometers Raman Spectrum HBCO Blood Detection Forensic Science HGB Hyperspectral imaging Materials Science thin film structural materials superlattice materials semiconductor material high temperature resistant materials carbon nano materials Hyperspectral Imagery for Oil Spill Detection the spectralum of microplastics Fluorescence imager Total organic carbon Time-of-flight mass analyzer X ray fluorescence ATR FT-IR spectrometer AAS NIR IR Water Quality Online Monitoring Solution ATH ATP ATF ATE UV GF GA Introduction to the optical path of a spectrometer