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Fluorescence is one of two kinds of emission of light by a substance that has absorbed light or other electromagnetic radiation. Fluorescence involves no change in electron spin multiplicity and generally it immediately follows absorption; phosphorescence involves spin change and is delayed. Thus fluorescent materials generally cease to glow nearly immediately when the radiation source stops, while phosphorescent materials, which continue to emit light for some time after.
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye. There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.
A waveguide is a structure that guides waves by restricting the transmission of energy to one direction. Common types of waveguides include acoustic waveguides which direct sound, optical waveguides which direct light, and radio-frequency waveguides which direct electromagnetic waves other than light like radio waves.
All-silica fiber, or silica-silica fiber, is an optical fiber whose core and cladding are made of silica glass. The refractive index of the core glass is higher than that of the cladding. These fibers are typically step-index fibers. The cladding of an all-silica fiber should not be confused with the polymer overcoat of the fiber.
In electromagnetics, an evanescent field, or evanescent wave, is an oscillating electric and/or magnetic field that does not propagate as an electromagnetic wave but whose energy is spatially concentrated in the vicinity of the source. Even when there is a propagating electromagnetic wave produced, one can still identify as an evanescent field the component of the electric or magnetic field that cannot be attributed to the propagating wave observed at a distance of many wavelengths.
Optical tweezers are scientific instruments that use a highly focused laser beam to hold and move microscopic and sub-microscopic objects like atoms, nanoparticles and droplets, in a manner similar to tweezers. If the object is held in air or vacuum without additional support, it can be called optical levitation.
Resonance Raman spectroscopy is a variant of Raman spectroscopy in which the incident photon energy is close in energy to an electronic transition of a compound or material under examination. This similarity in energy (resonance) leads to greatly increased intensity of the Raman scattering of certain vibrational modes, compared to ordinary Raman spectroscopy.
Fluorescence correlation spectroscopy (FCS) is a statistical analysis, via time correlation, of stationary fluctuations of the fluorescence intensity. Its theoretical underpinning originated from L. Onsager's regression hypothesis. The analysis provides kinetic parameters of the physical processes underlying the fluctuations. One of the interesting applications of this is an analysis of the concentration fluctuations of fluorescent particles (molecules) in solution. In this application, the fluorescence emitted from a very tiny space in solution containing a small number of fluorescent particles (molecules) is observed. The fluorescence intensity is fluctuating due to Brownian motion of the particles. In other words, the number of the particles in the sub-space defined by the optical system is randomly changing around the average number. The analysis gives the average number of fluorescent particles and average diffusion time, when the particle is passing through the space. Eventually, both the concentration and size of the particle (molecule) are determined. Both parameters are important in biochemical research, biophysics, and chemistry.
Autofluorescence is the natural emission of light by biological structures such as mitochondria and lysosomes when they have absorbed light, and is used to distinguish the light originating from artificially added fluorescent markers (fluorophores).
In radio-frequency engineering and communications engineering, waveguide is a hollow metal pipe used to carry radio waves. This type of waveguide is used as a transmission line mostly at microwave frequencies, for such purposes as connecting microwave transmitters and receivers to their antennas, in equipment such as microwave ovens, radar sets, satellite communications, and microwave radio links.
An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum. Common types of optical waveguides include optical fiber waveguides, transparent dielectric waveguides made of plastic and glass, liquid light guides, and liquid waveguides.
An aromatic amino acid is an amino acid that includes an aromatic ring.
The Earth–ionosphere waveguide is the phenomenon in which certain radio waves can propagate in the space between the ground and the boundary of the ionosphere. Because the ionosphere contains charged particles, it can behave as a conductor. The earth operates as a ground plane, and the resulting cavity behaves as a large waveguide.
Dansyl chloride or 5-(dimethylamino)naphthalene-1-sulfonyl chloride is a reagent that reacts with primary amino groups in both aliphatic and aromatic amines to produce stable blue- or blue-green–fluorescent sulfonamide adducts. It can also be made to react with secondary amines. Dansyl chloride is widely used to modify amino acids; specifically, protein sequencing and amino acid analysis. Dansyl chloride may also be denoted DNSC. Likewise, a similar derivative, dansyl amide is known as DNSA.
Single-molecule real-time (SMRT) sequencing is a parallelized single molecule DNA sequencing method. Single-molecule real-time sequencing utilizes a zero-mode waveguide (ZMW). A single DNA polymerase enzyme is affixed at the bottom of a ZMW with a single molecule of DNA as a template. The ZMW is a structure that creates an illuminated observation volume that is small enough to observe only a single nucleotide of DNA being incorporated by DNA polymerase. Each of the four DNA bases is attached to one of four different fluorescent dyes. When a nucleotide is incorporated by the DNA polymerase, the fluorescent tag is cleaved off and diffuses out of the observation area of the ZMW where its fluorescence is no longer observable. A detector detects the fluorescent signal of the nucleotide incorporation, and the base call is made according to the corresponding fluorescence of the dye.
Super-resolution microscopy is a series of techniques in optical microscopy that allow such images to have resolutions higher than those imposed by the diffraction limit, which is due to the diffraction of light. Super-resolution imaging techniques rely on the near-field or on the far-field. Among techniques that rely on the latter are those that improve the resolution only modestly beyond the diffraction-limit, such as confocal microscopy with closed pinhole or aided by computational methods such as deconvolution or detector-based pixel reassignment, the 4Pi microscope, and structured-illumination microscopy technologies such as SIM and SMI.
A single-photon source is a light source that emits light as single particles or photons. Single-photon sources are distinct from coherent light sources (lasers) and thermal light sources such as incandescent light bulbs. The Heisenberg uncertainty principle dictates that a state with an exact number of photons of a single frequency cannot be created. However, Fock states can be studied for a system where the electric field amplitude is distributed over a narrow bandwidth. In this context, a single-photon source gives rise to an effectively one-photon number state.
Plasmonics or nanoplasmonics refers to the generation, detection, and manipulation of signals at optical frequencies along metal-dielectric interfaces in the nanometer scale. Inspired by photonics, plasmonics follows the trend of miniaturizing optical devices, and finds applications in sensing, microscopy, optical communications, and bio-photonics.
Fluorescence is the emission of light by a molecule or an atom that has absorbed light or other electromagnetic radiation. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum, while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light.
Majed Chergui is a Swiss and French physicist specialized in ultrafast dynamics of light-induced processes. He is a professor at EPFL, head of the Laboratory of Ultrafast Spectroscopy at EPFL's School of Basic Sciences, and founding director of the Lausanne Centre for Ultrafast Science (LACUS).
References
- ↑ Jan Kieleczawa (2004). DNA sequencing: optimizing the process and analysis. Jones & Bartlett Publishers. p. 190. ISBN 978-0-7637-4782-4.
- ↑ D. H. Russell (Dec 1997). "The waveguide below-cutoff attenuation standard". IEEE Trans. Microwave Theory and Technology. 45 (12): 2408–2413. Bibcode:1997ITMTT..45.2408R. doi:10.1109/22.643852. S2CID 6236996.
- ↑ Baibakov, Mikhail; Barulin, Aleksandr; Roy, Prithu; Claude, Jean-Benoît; Patra, Satyajit; Wenger, Jérôme (1999-02-22). "Zero-mode waveguides can be made better: fluorescence enhancement with rectangular aluminum nanoapertures from the visible to the deep ultraviolet". Nanoscale Advances. 2 (9): 4153–4160. Bibcode:2020NanoA...2.4153B. doi: 10.1039/D0NA00366B . PMC 9417158 . PMID 36132755.
- ↑ Baibakov, Mikhail; Barulin, Aleksandr; Roy, Prithu; Claude, Jean-Benoît; Patra, Satyajit; Wenger, Jérôme (2020). "Zero-mode waveguides can be made better: fluorescence enhancement with rectangular aluminum nanoapertures from the visible to the deep ultraviolet". Nanoscale Advances. 2 (9): 4153–4160. Bibcode:2020NanoA...2.4153B. doi:10.1039/D0NA00366B. PMC 9417158 . PMID 36132755.
- ↑ Barulin, Aleksandr; Roy, Prithu; Claude, Jean-Benoît; Wenger, Jérôme (2021-10-21). "Purcell radiative rate enhancement of label-free proteins with ultraviolet aluminum plasmonics". Journal of Physics D: Applied Physics. 54 (42): 425101. arXiv: 2107.06357 . Bibcode:2021JPhD...54P5101B. doi:10.1088/1361-6463/ac1627. ISSN 0022-3727. S2CID 235829393.
- ↑ Barulin, Aleksandr; Claude, Jean-Benoît; Patra, Satyajit; Bonod, Nicolas; Wenger, Jérôme (9 October 2019). "Deep Ultraviolet Plasmonic Enhancement of Single Protein Autofluorescence in Zero-Mode Waveguides". Nano Letters. 19 (10): 7434–7442. arXiv: 1909.08227 . Bibcode:2019NanoL..19.7434B. doi:10.1021/acs.nanolett.9b03137. PMID 31526002. S2CID 202660648.
- ↑ Barulin, Aleksandr; Roy, Prithu; Claude, Jean-Benoît; Wenger, Jérôme (5 April 2022). "Ultraviolet optical horn antennas for label-free detection of single proteins". Nature Communications. 13 (1): 1842. arXiv: 2204.02807 . Bibcode:2022NatCo..13.1842B. doi: 10.1038/s41467-022-29546-4 . PMC 8983662 . PMID 35383189.
- ↑ Roy, Prithu; Claude, Jean-Benoît; Tiwari, Sunny; Barulin, Aleksandr; Wenger, Jérôme (5 January 2023). "Ultraviolet Nanophotonics Enables Autofluorescence Correlation Spectroscopy on Label-Free Proteins with a Single Tryptophan". Nano Letters. 23 (2): 497–504. arXiv: 2301.01516 . Bibcode:2023NanoL..23..497R. doi:10.1021/acs.nanolett.2c03797. PMID 36603115. S2CID 255416119.
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