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LIF-EEM Engineering Design
Published in Katherine Balshaw-Biddle, Carroll L. Oubre, C. H. Ward, Subsurface Contamination Monitoring Using Laser Fluorescence, 2019
Katherine Balshaw-Biddle, Carroll L. Oubre, C. H. Ward
Use of laser-induced fluorescence (LIF) technology for in situ contaminant monitoring is based upon the principle that many petroleum hydrocarbons absorb laser energy and quickly release the excess energy by emitting light, i.e., fluorescing. The LIF-excitation–emission matrix (EEM) system generates the laser light, delivers it to the remote sample using fiber optics, collects and delivers the resulting emission from the fluorescing hydrocarbons to a detector, and records the signal electronically. The Tufts system design advances the state of the art of in situ LIF by delivering multiple excitation wavelengths and detecting fluorescence as a function of both excitation and emission wavelengths to create a three-dimensional fingerprint of the contaminant. This can be accomplished in situ during a CPT sounding, thus providing real-time measurements of contaminant distribution.
Applications of Laser-Induced Fluorescence Spectroscopy for Combustion and Plasma Diagnostics
Published in Leon J. Radziemski, Richard W. Solarz, Jeffrey A. Paisner, Laser Spectroscopy and Its Applications, 2017
For many LIF experiments, especially molecular fluorescence, light is usually collected from numerous levels other than the level directly excited by the laser. Collisional and radiative transfer between energy levels in a laser-excited molecule or atom is usually the most important consideration for quantitative measurements of concentration or temperature. Laser-induced fluorescence is an indirect measurement of ground-state populations of atoms or molecules, and it is important to understand the population dynamics that occur when a species is excited by laser radiation.
Laser induced fluorescence detection of R6G dye adsorbed on Fe3O4 nanomaterials
Published in Journal of Applied Water Engineering and Research, 2022
Yasmin El-Dakrory, Mahmoud Sliem, Maha Abdelkreem, Salah Hassab Elnaby, Reham Rezk
Laser-induced fluorescence (LIF) spectroscopy is a sensitive and powerful technique for detecting molecules and atoms, measuring species concentrations, and energy-level population distributions. LIF provides fluorescent dye emission at longer wavelengths than the excitation wavelength. Fluorescence occurs when a molecule absorbs photons from the UV-visible light spectrum (200-900 nm), causing a transition to a high energy electronic state and then emitting photons as it returns to its initial state in 10–9 sec approximately. The molecule energy is lost through heat or vibration; so that emitted energy is less than the exciting energy; i.e. the emission wavelength is always longer than the excitation wavelength (Crimaldi, 2008).