CIQTEK X-band pulse electron paramagnetic resonance (EPR or ESR) spectroscopy EPR100 supports both continuous-wave EPR and pulse EPR functions, satisfying general CW EPR experiments while performing T1 /T2 / ESEEM (electron-spin echo envelope modulation) / HYSCORE (hyperfine sublevel correlation) and other pulsed EPR tests, which can achieve higher spectral resolution and reveal ultra-fine interactions between electrons and nuclei, thus providing users with more information about the structure of matter.
>> Optionally equipped with a 4-300 K variable temperature device to enable the detection of paramagnetic substances at ultra-low (high) temperatures.
>> EPR100 Accessories:
Dual Mode Resonator; High-temperature System; Liquid Nitrogen Variable Temperature With Cryostat; Liquid Helium Variable Temperature; Liquid Helium-free Dry Cryogenic System; Time-resolved EPR System; ELDOR System; ENDOR System; Goniometers; Irradiation System; Flat Cell.
Stable magnetic fields with precise scanning control and over-zero field scanning technique.
Sequence generator with an unlimited number of pulses for kinetic decoupling techniques with a large number of pulses.
Up to 450 W pulse power with high-performance pulse EPR probe for more efficient narrow pulse excitation.
Microwave pulse time resolution up to 50 ps for improved spectral line resolution in pulse mode.
>> High Precision Digital Time Delay Pulse Generation Control
The high-precision digital time delay pulse generator with 50 ps time resolution accuracy provides a more accurate timing control function, which can be combined with table or code sequence editing to complete various pulse experiments more efficiently.
>> Advanced Liquid Helium-free Variable Temperature System
Dry, liquid helium-free cryogenic systems for variable temperature control in experiments, with no liquid helium consumption during use, continuous operation, greater safety, better environmental protection, and lower operating costs.
>> Support for Upgrading High Frequency
Support for upgrading some modules makes the whole machine upgrade to Q-band, W-band, and other higher frequency band EPR spectroscopy for high-frequency EPR research.
By studying the electron-electron interactions, distance detection between paramagnetic species in close proximity to physiological reactions or chemical reaction environments can be achieved.
The hyperfine and nuclear quadrupole moment interactions of electrons with nuclei can be detected.
The pulse output of arbitrary waveform can be realized, and the amplitude, phase, frequency, and waveform envelope of the pulse can be modified to perform customized and complex pulse experiments.
The combination of time-resolved techniques with paramagnetic resonance spectroscopy can be used to study transients such as free radicals or excited triplet states during fast reactions.
EPR Application Cases
EPR Detection of Free Radicals
Free radicals are atoms or groups with unpaired electrons that are formed when a compound molecule is subjected to external conditions such as light or heat and the covalent bonds are split. For more stable free radicals, EPR can detect them directly and quickly. For short-lived free radicals, they can be detected by spin trapping. For example, hydroxyl radicals, superoxide radicals, single-linear oxygen light radicals, and other radicals produced by photocatalytic processes.
Paramagnetic Metal lons
For transition metal ions (including iron, palladium, and platinum group ions with unfilled 3d, 4d, and 5d shell respectively) and rare earth metal ions (with unfilled 4f shell), these paramagnetic metal ions can be detected by EPR spectrometer due to the presence of the single electrons in their atomic orbitals, thus obtaining the valence and structure information. In the case of transition metal ions, there are usually multiple valence states and spin states with high and low spins. Parallel modes in a two-mode cavity allow detection of the integer spin regime.
Conduction Electrons in Metal
The EPR line shape that conducts electrons is related to the size of the conductor, which is of great significance in the field of lithium-ion batteries. EPR can non-invasively probe the interior of the battery to study the deposition process of lithium in a close-to-real situation, from which the microscopic size of metallic lithium deposits can be inferred.
Material Doping And Defects
Metallofullerenes, as new nanomagnetic materials, have significant application value in magnetic resonance imaging, single-molecule magnets, spin quantum information, and other fields. Through EPR technology, the electron spin distribution in metallofullerenes can be obtained, providing an in-depth understanding of the ultrafine interaction between spin and the magnetic nucleus of metals. It can detect changes in spin and magnetism of metallofullerenes in different environments. (Nanoscale 2018, 10, 3291)
Photocatalysis
Semiconductor photocatalytic materials have become a hot research topic due to their potential applications in environmental, energy, selective organic transformation, medical, and other fields. EPR technology can detect active species generated on the surface of photocatalysts, such as e-, h+, •OH, O2, 1O2, SO3, etc. It can detect and quantify vacancies or defects in photocatalytic materials, assist in studying active sites and reaction mechanisms of photocatalytic materials, optimize parameters for subsequent photocatalytic application processes, detect active species and their proportions during photocatalysis, and provide direct evidence for system reaction mechanisms. The figure shows the EPR spectra of 0.3-NCCN and CN, indicating that 0.3-NCCN contains more unpaired electrons, higher crystallinity, and an extended p-conjugated system, resulting in better photocatalytic performance. (International Journal of Hydrogen Energy, 2022, 47: 11841-11852)
EPR Spectra, 3P-ESEEM spectrum of CoTPP(py)
EPR Spectra, ENDOR spectra of coal samples