Editing Stokes shift (section)

== Applications of Stokes and anti-Stokes shifts ==

=== Raman spectroscopy ===
In [[Raman spectroscopy]], when a molecule is excited by incident radiation, it undergoes a Stokes shift as it emits radiation at a lower energy level than the incident radiation. Analyzing the intensity and frequency of the spectral shift provides valuable information about the vibrational modes of molecules, enabling the identification of chemical bonds, functional groups, and molecular conformations.

=== Yttrium oxysulfide ===
[[Yttrium]] oxysulfide ({{Chem2|Y2O2S}}) doped with [[gadolinium oxysulfide]] ({{Chem2|Gd2O2S}}) is a common industrial anti-Stokes [[pigment]], absorbing in the [[Infrared#Regions within the infrared|near-infrared]] and emitting in the visible region of the spectrum.<ref>{{Cite journal |last=Georgobiani |first=A. N. |last2=Bogatyreva |first2=A. A. |last3=Ishchenko |first3=V. M. |last4=Manashirov |first4=O. Ya. |last5=Gutan |first5=V. B. |last6=Semendyaev |first6=S. V. |date=2007-10-01 |title=A new multifunctional phosphor based on yttrium oxysulfide |url=https://doi.org/10.1134/S0020168507100093 |journal=Inorganic Materials |language=en |volume=43 |issue=10 |pages=1073–1079 |doi=10.1134/S0020168507100093 |issn=1608-3172|url-access=subscription }}</ref> This composite material is often utilized in luminescent applications, where it absorbs lower-energy photons and emits higher-energy photons. This unique property makes it particularly valuable in various technological fields, including security printing, anti-counterfeiting measures, and luminescent displays. By harnessing anti-Stokes fluorescence, this pigment enables the creation of vibrant and durable inks, coatings, and materials with enhanced visibility and authentication capabilities.

=== Photon upconversion ===
[[Photon upconversion]] is an anti-Stokes process where lower-energy photons are converted into higher-energy photons. An example of this later process is demonstrated by [[upconverting nanoparticles]]. It is more commonly observed in [[Raman spectroscopy]], where it can be used to determine the temperature of a material.<ref name="Keresztury2">{{Cite book |last=Keresztury |first=Gábor |title=Handbook of Vibrational Spectroscopy |publisher=Wiley |year=2002 |isbn=0471988472 |volume=1 |location=Chichester |chapter=Raman Spectroscopy: Theory}}</ref>

=== Optoelectronic devices ===
In direct-bandgap thin-film semiconducting layers Stokes shifted emission can originate from three main sources: doping, strain, and disorder.<ref>{{Cite journal |author1=Pavel V. Kolesnichenko |author2=Qianhui Zhang |author3=Tinghe Yun |author4=Changxi Zheng |author5=Michael S. Fuhrer |author5-link=Michael Fuhrer |author6=Jeffrey A. Davis |year=2020 |title=Disentangling the effects of doping, strain and disorder in monolayer WS2 by optical spectroscopy |url=https://iopscience.iop.org/article/10.1088/2053-1583/ab626a |journal=[[2D Materials (journal)|2D Materials]] |volume=7 |issue=2 |pages=025008 |arxiv=1909.08214 |doi=10.1088/2053-1583/ab626a |s2cid=202661069}}</ref> Each of these factors can introduce variations in the energy levels of the semiconductor material, leading to a shift in the emitted light towards longer wavelengths compared to the incident light. This phenomenon is particularly relevant in optoelectronic devices where controlling these factors can be crucial for optimizing device performance.