EPR (Electron Paramagnetic Resonance) Spectroscopy, also known as Electron Spin Resonance (ESR) Spectroscopy, is a technique used to study the electronic structure of paramagnetic species.

There are two main types of EPR spectroscopy: Continuous Wave (CW) EPR spectroscopy and Pulsed EPR spectroscopy.

Continuous wave (CW) EPR Spectroscopy:

In continuous wave EPR spectroscopy, a microwave source continuously emits microwave radiation at a fixed frequency into the sample.

A magnetic field is swept over a range of frequencies and the absorption of the microwave radiation by the sample is measured as a function of the magnetic field strength. This produces an EPR spectrum showing the jumps between energy levels of paramagnetic species.

CW EPR spectroscopy is commonly used to study relatively slow dynamic processes and to examine stable paramagnetic species.

Pulsed EPR Spectroscopy:

Pulsed EPR spectroscopy, also known as pulsed electron-electron double resonance (ELDOR) or electron-electron resonance, utilizes short pulses of electromagnetic radiation. This technique is used to study the dynamics of paramagnetic species and their interactions with their surroundings.

Pulsed EPR spectroscopy provides more detailed information and allows the measurement of relaxation times, distances, and other dynamic parameters. It involves applying microwave pulses, often combined with radio frequency (RF) pulses, to manipulate the electron spin state and measure the resulting signal.

Pulsed EPR techniques include Electron Spin Echo (ESE), Electron Nuclear Dual Resonance (ENDOR), Electron Spin Echo Envelope Modulation (ESEEM), and others.

Pulsed EPR spectroscopy is particularly well suited for the study of transient species, radical reactions, and spin-spin interactions in paramagnetic systems.

Both CW EPR and pulsed EPR spectroscopy have their advantages and applications, depending on the specific research objectives and the properties of the paramagnetic species under study.

CIQTEK offers X-Band Pulse EPR Spectroscopy | EPR100 and X-Band CW-EPR Spectroscopy | EPR200-Plus

The Scanning Electron Microscope (SEM) is a powerful tool for various applications in material sciences, life sciences, and other fields. Different kinds of detectors have been developed to obtain more information and improve the performance of SEM. The following are a few common types of SEM detectors:

Backscattered Electron Detector (BSE): BSE detectors are used to detect electrons scattered by the nuclei of atoms and high atomic number elements within a substance.BSE detectors provide high-contrast images that can be used for compositional analysis of materials and characterization of microstructures.

Secondary Electron Detector (SE): The SE detector is used to detect secondary electrons on the surface of a material excited by a scanning electron beam. Since the surface morphology and material composition influence the secondary electrons, the SE detector provides a high-resolution image of the surface topography.

Transmission Electron Detector (TED): TED detectors are used to detect transmission electrons that pass through a thin sheet of material and are focused on the detector. TED detectors are suitable for high-resolution compositional and structural analyses of materials, e.g., atomic-level characterization of nanoparticles.

Energy Dispersive X-ray Spectroscopy (EDS): EDS detectors are used to analyze the elemental composition of materials. When a scanning electron beam interacts with a sample, characteristic X-rays are produced, and the EDS detector collects and measures the energy spectrum of these X-rays to determine the chemical composition and elemental distribution of the material.

Retarding Field Detector (RFD): The RFD detector is used to measure the charge carried by electrons generated on the surface of the sample. This type of detector is very useful for studying the electrical conductivity and surface charge properties of materials.

These are just some of the common SEM detectors; in fact, there are many other types of detectors, each with different advantages and applications. The selection of the appropriate detector depends on the objectives of the study and the information to be obtained.

CIQTEK's self-developed SEM offers a wide range of detectors to choose from, such as BSED, STEM, EDS, EDX, EBSD, In-lens, ETD, etc. 

ESR (Electron Spin Resonance) and EPR (Electron Paramagnetic Resonance) are used interchangeably to describe the same spectroscopic technique. The reason for the two different names can be traced to the historical development of the field and some of the interesting stories surrounding it.

Originally, the technique was called ESR, or electron spin resonance. It was discovered in the mid-20th century by physicists studying the behavior of electrons in magnetic fields. They observed that certain materials absorbed energy at specific frequencies when exposed to strong magnetic fields and subjected to electromagnetic radiation. This absorption is due to the electron spin states flipping in the magnetic field, resulting in resonance.

As the field grew, researchers began to study the spectra of paramagnetic species - atoms, molecules, or ions with unpaired electrons. They realized that ESR techniques could be used to study a wider range of systems than just electrons. As a result, the term EPR (Electron Paramagnetic Resonance) was coined to encompass a broader range of applications.

The transition from ESR to EPR did not happen overnight or with universal adoption. Different research groups and scientific communities preferred to use either term. For example, the term ESR was widely used in the United States, while EPR became popular in Europe. This difference in naming conventions continued for some time until the two terms gradually became synonymous. Today, the two terms are widely accepted and used interchangeably to describe the same spectroscopic techniques.

The dual naming of ESR and EPR provides insight into the historical development of the field and how scientific terminology has evolved and adapted over time. It also serves as a reminder that in science, different cultures and communities may adopt different names for the same concept, and these differences may persist until a consensus is reached.

EPR spectroscopy has applications in a variety of fields including chemistry, physics, biochemistry, materials science, and medicine. It has been used to study the structure of metalloproteins, the mechanism of enzyme reactions, the properties of organic radicals, the behavior of transition metal complexes, and defects in semiconductors, as well as many other fascinating areas of research. Its ability to probe electron spin makes it an invaluable tool for understanding the fundamental properties of paramagnetic systems and exploring their role in a variety of physical and chemical processes.

>> Check more about CIQTEK EPR spectroscopy.

There are several scanning electron microscope manufacturers in Korea.

The following are some of the famous companies:

JEOL LIMITED: JEOL is a manufacturer of scientific instruments and equipment, including scanning electron microscopes. They offer a range of scanning electron microscope models with different specifications and applications.

Hitachi High-Tech Korea Co., Ltd: Hitachi High-Tech Korea is a subsidiary of Hitachi High-Tech Corporation, a global technology company. They offer a wide range of scientific instruments for research and industrial applications, including scanning electron microscopes.

Samsung Electronics Co. Ltd: Samsung Electronics is a leading South Korean multinational company that produces a wide range of products including consumer electronics and industrial equipment. They also produce advanced electron microscopes, including scanning electron microscopes.

S-Connect Co., Ltd: S-Connect is a South Korean company specializing in the development and manufacture of scientific instruments. They offer customized scanning electron microscopes for a variety of research and industrial applications.

TESCAN Korea Co., Ltd.: TESCAN is a global supplier of scientific instruments including scanning electron microscopes. With a branch office in Korea, the company provides SEM solutions for materials science, life science, and other fields.

CIQTEK Co., Ltd.: CIQTEK is a global manufacturer of high-value scientific instruments including Scanning Electron Microscope (SEM).

CIQTEK's SEM products offer advanced microscope technology and innovative features that provide high-resolution surface topography and compositional analysis. 

In addition, CIQTEK provides SEM-related technical support and training services to help users realize the full potential of SEM. They have a professional team with extensive experience and knowledge to provide consulting and solutions.

Check the CIQTEK SEM microscope here.

Research each company's products, specifications, and customer reviews to find the best SEM for specific needs.

Electron Paramagnetic Resonance (EPR) spectrometers are widely used in research institutions, universities, and industrial laboratories in South Korea. Major brands of EPR spectrometers in Korea include Jeol, Bruker, Nicolet, and CIQTEK. Below are the features and prices of these EPR companies.

Jeol

Features: Jeol is a time-honored brand known for its high-quality and reliable instruments. On the downside, the cost is relatively high compared to other brands. In addition, depending on the specific model, their instruments may have limited flexibility regarding modular configuration and specialized accessories.

Bruker

Features: Bruker is a well-known EPR spectrometer company. Their spectrometers are known for their high sensitivity, advanced signal processing capabilities, and ruggedness. However, it is costly and the complexity of the instrument software may require a learning curve for new users.

CIQTEK

CIQTEK EPR spectrometers are technologically advanced with world-leading resolution and sensitivity. Also featuring a user-friendly software interface that is easy to use for beginners, CIQTEK's wide range of EPR spectrometers is equipped with a variety of specialized accessories and options for versatility in experimental setups. It is more affordable. Saves time and budget.

  https://www.ciqtekglobal.com

Nicolet (Thermo Fisher Scientific)

Features: Nicolet EPR spectrometers from Thermo Fisher Scientific are renowned for their accuracy, reliability, and ease of use, with excellent signal-to-noise ratios and sensitivity for a wide range of EPR applications. They have excellent signal-to-noise ratios and sensitivity for a wide range of EPR applications. One potential drawback of Nicolet EPR spectrometers compared to other brands is their limited availability of specialized accessories and options, which may limit certain experimental setups or specific research needs.

It's worth noting that the prices mentioned above are rough estimates and can vary depending on the specific configuration and region. Additionally, each brand may offer different models with varying specifications and price ranges.

Scanning electron microscopes (SEMs) are highly advanced and sophisticated scientific instruments that provide high-resolution imaging and analysis of samples at the nanoscale level. There are several renowned scanning electron microscope brands available in Europe that offer state-of-the-art SEMs. Here are a few notable brands:

FEI Company (Thermo Fisher Scientific): FEI Company is a leading provider of high-performance electron microscopy solutions. They offer a range of SEMs, including the highly regarded "Quanta" series, known for their exceptional imaging capabilities and versatility.

Zeiss Microscopy: Zeiss is a renowned German manufacturer of various optical and electron microscopy instruments. Their SEMs, such as the "MERLIN" and "EVO" series, are known for their advanced imaging technologies, user-friendly interfaces, and precise analytical capabilities.

Hitachi High-Tech: Hitachi is a well-established Japanese company with a strong European presence. Hitachi SEMs, like the "SU5000" and "TM4000," are known for their excellent imaging quality, robustness, and a wide variety of applications.

JEOL Ltd.: JEOL is a global leader in electron microscopy and analytical instrumentation. Their SEMs, including the "JSM" series, are renowned for their high-resolution imaging, advanced analytical capabilities, and user-friendly interfaces.

CIQTEK: CIQTEK is a global supplier and manufacturer of scanning electron microscopes and other high-end analytical instruments. Their tungsten filament scanning electron microscope SEM3200, field emission scanning electron microscope SEM4000 / SEM5000, ultra-high resolution field emission scanning electron microscope SEM5000X, and focused ion beam scanning electron microscope DB500, are high-performance and at competitive prices. 

TESCAN: TESCAN is a Czech company that specializes in manufacturing SEMs and other electron microscopy instrumentation. Their SEMs, such as the "VEGA" and "MIRA" series, are esteemed for their outstanding image quality, accurate sample manipulation, and extensive imaging modes.

These are just a few reputable brands offering scanning electron microscopes in Europe. Prices for SEMs in Europe can vary significantly depending on specifications, accessories, and additional features. It's recommended to directly contact the manufacturers or authorized distributors to obtain accurate pricing information based on the specific requirements.

Electron paramagnetic resonance (EPR) spectroscopy is a powerful technique used to study the electronic structure of paramagnetic substances. It provides valuable insights into the nature and interactions of unpaired electrons in magnetic fields. Selection rules in EPR spectroscopy establish conditions that allow or prohibit leaps between different energy levels. Understanding these selection rules is essential for data interpretation and extracting meaningful information from EPR spectra.

Rotational selection rules in EPR

The most basic EPR spectroscopy selection rule is the spin selection rule. It states that for an electron jump to occur, the spin projection quantum number (m_s) must change by ±1. The m_s value describes the orientation of the electron spin for an external magnetic field. This shift can be caused by a spin flip (parallel to antiparallel or vice versa) or spin conservation (parallel to parallel or antiparallel to antiparallel).

Magnetic quantum number selection rules in EPR

The magnetic quantum number (m_l) selection rule is also important in EPR spectroscopy. It states that the change in m_l value due to transitions must be ±1. The m_l value is related to the component of angular momentum of the electron along the magnetic field axis. EPR leaps usually involve a change in the angular momentum of the electron orbitals, which results in a change in the m_l value.

Transition selection rules in EPR

Another important selection rule in EPR spectroscopy is the transition selection rule. It states that only allowed leaps will be observed in the EPR spectrum according to the spin and magnetic quantum number selection rules. No forbidden transitions that violate the selection rule will be detected. This rule facilitates the interpretation and assignment of spectral features.

Forbidden transitions in EPR

Although forbidden leaps strictly violate the selection rule, they sometimes occur with very low probability. Forbidden leaps are usually caused by weak interactions, such as spin-orbit coupling, which couples spin and orbital angular momentum. These leaps are usually observed as weaker spectral features compared to the allowed leaps.

Thus, selection rules play a key role in EPR spectroscopy, controlling the transitions between the energy levels of paramagnetic matter. Spin selection rules, magnetic quantum number selection rules, and lepton selection rules identify allowed and forbidden leaps that enable the interpretation and analysis of EPR spectra. Understanding these selection rules helps researchers extract valuable information about the electronic structure, spin dynamics, and magnetic properties of paramagnetic systems when using EPR spectroscopy.

CIQTEK EPR spectrometers are simple and easy to use, providing researchers with a user-friendly operating environment.

The g-value plays a crucial role in EPR (Electron Paramagnetic Resonance) spectroscopy in understanding the electronic structure and magnetic properties of paramagnetic substances. Today, we will talk about the key factor in EPR spectroscopy: the g-value (g-factor).

The g-value is a dimensionless quantity that represents a constant of proportionality between the magnetic field and the energy difference between the energy levels in the system. The g-value can be obtained by measuring the resonance frequency of a paramagnetic substance absorbing electromagnetic radiation in the presence of a magnetic field. It represents the extent to which the electron spin interacts with the external magnetic field. The g value is commonly used to determine important characteristics of paramagnetic substances, such as the number of unpaired electrons and their orbital angular momentum.

For a free electron, the g value is a constant of 2.0023, derived from fundamental physical properties. However, in more complex systems, such as transition metal complexes or organic radicals, the g value can deviate from this standard value. The deviation arises due to various factors, including spin-orbit coupling and hyperfine interactions with nearby nuclei. These interactions introduce additional energy levels and modify the electron's behavior in the magnetic field, leading to different g values.

By analyzing the g value in EPR spectroscopy, scientists can gain insights into the molecular structure and chemical environment of the paramagnetic species under investigation. A change in the g value can reveal the presence of different ligands or coordination environments around a metal ion, providing valuable information about the electronic configuration and coordination chemistry.

In addition, the g-value can be used to study the dynamics of a system. For example, it can provide information about the rate of electron transfer or spin relaxation processes, revealing the kinetics and mechanisms involved in chemical reactions or biological processes.

A common method of measuring the g-value is using EPR spectroscopy on a sample with a known g-value. This reference sample can be a compound with a well-characterized g-value or a spin probe, such as a stable organic radical. By comparing the position and shape of the resonance signals of the reference sample and the sample of interest, the g-value of the unknown species can be calculated.

Another approach involves calculating the g value from the Zeeman effect. The Zeeman effect describes the splitting of energy levels in a magnetic field. By measuring the magnetic field strength required to observe resonance at different frequencies, the g value can be derived using the equation g = hν/μBΔB, where h is Planck's constant, ν is the microwave frequency, μB is the Bohr magneton, and ΔB is the magnetic field difference between the resonance peaks.

In addition, the g value can be determined by analyzing the linewidth of the EPR signal. Since the g value depends on the orientation of the unpaired electrons in the magnetic field, any interaction or fluctuation in the environment will broaden the EPR signal. The g-value can be estimated by measuring the linewidth and analyzing its dependence on the magnetic field strength.

It is worth noting that the g value is not always a fixed constant. In some cases, it may vary due to factors such as electron-electron interactions or electrons leaving the domain. These variations can indicate the chemical or physical properties of the paramagnetic substance.

In summary, the g-value in EPR spectroscopy is an important parameter that helps characterize paramagnetic substances. By determining the g-value, researchers can gain valuable insights into the electronic structure and properties of paramagnetic compounds, contributing to understanding a wide range of scientific disciplines, including chemistry, physics, and biology.

Click here to read more application notes on EPR spectroscopy.

In the field of analytical instrumentation, both Electron Spin Resonance (ESR) spectrometers and Nuclear Magnetic Resonance (NMR) spectrometers play an important role. Although they use similar principles, there are significant differences between the two techniques.

ESR Spectrometer:

Electron Spin Resonance (ESR) spectrometers are employed to study the behavior of unpaired electrons within a sample. Unpaired electrons possess a magnetic moment and can be analyzed using microwave radiation. ESR spectrometers use a strong magnetic field to split the energy levels of these electrons and measure the energy absorption or emission during electron spin transitions.

CIQTEK EPR Spectrometers

NMR Spectrometer:

On the other hand, Nuclear Magnetic Resonance (NMR) spectrometers focus on the study of the nuclear spins of atoms within a sample. Nuclei possessing an odd number of protons or neutrons have a non-zero nuclear spin and behave like tiny magnets. NMR spectrometers employ a strong magnetic field and radiofrequency pulses to excite and detect the nuclear spins, generating a signal that can be analyzed.

NMR Image Frrom Internet

Key Differences between ESR and NMR:

Target: ESR spectrometers focus on unpaired electrons, while NMR spectrometers examine the nuclear spins of atoms.

Technique: ESR utilizes microwaves, while NMR employs radiofrequency pulses.

Sample Types: ESR can analyze paramagnetic materials and free radicals, while NMR is widely used for organic compounds, proteins, and other molecules.

Applications: 

ESR

- The investigation of free radicals in biological systems. It helps scientists understand the role of free radicals in various diseases and the effects of antioxidants on their stability. 

- The study of paramagnetic materials, which have unpaired electrons and exhibit unique magnetic properties.

NMR

- In chemistry, particularly in determining the structure of organic compounds, researchers use NMR to decipher the connectivity of atoms within a molecule, providing vital information about its composition and spatial arrangement. 

- In biological research, such as studying protein structure and dynamics.

Price:

ESR spectrometers are generally less expensive than NMR spectrometers, making them more accessible to smaller research labs and educational institutions.

NMR spectrometers are sophisticated instruments and typically more costly due to their complex design, higher magnetic field strengths, and advanced capabilities.

Conclusion:

ESR and NMR spectrometers differ in their target entities, techniques, and applications. ESR explores unpaired electrons, while NMR focuses on nuclear spins. Both instruments contribute significantly to scientific advancements, enabling researchers to unravel the mysteries of matter at the atomic and molecular levels.

What are free radicals?

Free radicals are highly reactive molecules or atoms that play a crucial role in various chemical and biological processes. Understanding their behavior and detecting their presence is essential to studying their involvement with disease progression, environmental pollution, and other biological and chemical systems.

Image via the Internet

Principles of EPR Spectroscopy

EPR spectroscopy utilizes the magnetic properties of unpaired electrons in paramagnetic substances. When samples containing such substances are subjected to magnetic fields and electromagnetic radiation, electron spin transitions occur, resulting in the absorption or emission of energy. By measuring the occurrence of these transitions, valuable information about the paramagnetic substance and its environment can be obtained.

Application of EPR Spectroscopy in Free Radical Detection

Electron Paramagnetic Resonance (EPR) spectroscopy, also known as Electron Spin Resonance (ESR), is a powerful analytical technique used to study paramagnetic species, including free radicals. Free radicals play a crucial role in various chemical and biological processes, and their detection and understanding are essential for a range of applications. Since free radicals have unpaired electrons, they can be detected and characterized using EPR spectroscopy. This report explores the application of EPR spectroscopy in free radical detection.

1. Chemical Reactions

EPR spectroscopy provides valuable insights into the kinetics and mechanisms of free radical reactions in chemical systems. By monitoring changes in the EPR spectra during a reaction, researchers can determine the formation and consumption rates of free radicals, elucidate reaction pathways, and assess the effectiveness of radical scavengers or inhibitors.

2. Biological Systems

In biological systems, free radicals are involved in several physiological and pathological processes. EPR spectroscopy can be employed to study the generation, localization, and reactivity of free radicals in living organisms. By using spin traps or spin probes that selectively interact with specific radicals, researchers can gain insights into oxidative stress, inflammation, and disease progression.

3. Material Science

Free radicals can be formed and trapped in materials during their synthesis or under specific conditions. EPR spectroscopy allows for the detection and characterization of these trapped radicals, enabling researchers to explore their effects on the material's properties. This information contributes to the development of materials with improved performance and stability.

Conclusions

EPR spectroscopy has proven to be a valuable tool in the field of free radical detection, with applications spanning a variety of fields, including chemical reactions, biological systems, and materials science. Through the use of EPR spectroscopy, researchers can gain insight into the nature, behavior, and effects of free radicals, and thus better understand the role of free radicals in a wide range of processes.

CIQTEK has been deeply engaged in the field of EPR technology for many years and has independently developed a variety of EPR spectrometers for different research purposes, including benchtop EPR, floor-standing EPR, continuous wave EPR, pulsed EPR, etc.