Resonance Enhanced Multiphoton Ionization
Resonance Enhanced Multiphoton Ionization - Related Videos
03:12
Ionization Energy
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2020
The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy (IE1). The first ionization energy for an element, X, is the energy required to form a cation with 1+ charge: The energy required to remove the second most loosely bound electron is called the second ionization energy (IE2). The energy required to remove the third electron is the third ionization energy, and so on. Energy is always required...
09:38
Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer
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Cited by 3 •
2013
Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging of small molecules; protocols for the use of DT for the MALDI imaging of endogenous lipids on the surface of tissue sections by positive-ion MALDI-MS on an ultrahigh-resolution quadrupole-FTICR instrument are provided here.
10:03
Multiphoton Microscopy of Cleared Mouse Brain Expressing YFP
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Cited by 11 •
2012
Multiphoton microscopy of whole mouse organs is possible by optically clearing the organ before imaging, but not all protocols preserve the fluorescent signal of fluorescent proteins. Using an optical clearing method with ethanol-based dehydration and benzyl alcohol:benzyl benzoate clearing, we show high-resolution multiphoton images of whole mouse brain expressing YFP.
06:24
Dynamic Contrast Enhanced Magnetic Resonance Imaging of an Orthotopic Pancreatic Cancer Mouse Model
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Cited by 9 •
2015
The goal of this protocol is to apply dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for orthotopic pancreatic tumor xenografts in mice. DCE-MRI is a non-invasive method to analyze microvasculature in a target tissue, and useful to assess vascular response in a tumor following a novel therapy.
02:52
Resonance
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2020
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O bonds. If nitrite ions do indeed contain a single and a double bond, the two bond lengths are expected to be different. A double bond between two atoms is shorter (and stronger) than a single bond between the same two atoms. However, experiments show that both N–O bonds in NO2− have the same strength and length, and are identical in all other...
FAQs
The resonant intermediate state provides a selective pathway between photon absorption and ionization. Because the laser wavelength can be tuned to match this real state, the measurement can favor a chosen atomic or molecular species within a mixture. This wavelength dependence is central to chemical discrimination and helps connect ion signals with electronic structure.
Ion formation occurs in stages rather than through a single absorption event. The species first absorbs photons that promote it to a real intermediate state, and subsequent photon absorption supplies the energy needed to cross the ionization threshold. Separating resonance from the final ionization step explains how REMPI combines spectroscopic information with selective ion detection.
Laser wavelength and the number of absorbed photons are key conditions. Wavelength determines whether the species reaches its resonant intermediate state, while additional photons must provide enough energy to exceed the ionization threshold. Together, these requirements influence which species produces ions and therefore affect chemical discrimination and detection sensitivity.
A typical workflow begins by directing a tunable laser at the neutral atoms or molecules under investigation. The selected species absorbs photons through a resonant intermediate state and then absorbs additional photons for ionization. The resulting ions are transferred to time-of-flight mass spectrometry, where their signals can be analyzed alongside the laser wavelength.
Engineering studies can apply REMPI to combustion diagnostics, plasma monitoring, and atmospheric analysis. Its wavelength-selective ion production helps distinguish chemical species in complex environments, while its sensitivity supports detection when the measured species may be difficult to observe directly. These capabilities make it useful for investigating composition and electronic behavior in engineered systems.
The technique supports real-time studies of reactive or transient species by combining selective laser excitation with ion analysis. Tuning the laser toward a relevant resonant transition can improve discrimination from other constituents, while time-of-flight mass spectrometry provides a way to examine the ions produced. This is valuable in rapidly changing combustion, plasma, or atmospheric environments.