Diagram of apparatus
(Click figure to enlarge)
(c)
Waveform of EPR signal
(Click photo to enlarge)
Standing wave distribution in cavity
(Click figure to enlarge)
Note: oscilloscope not included
Features
Simple structure
Ample experimental examples
Stable performance
Introduction
Electron spin resonance, also known as electron paramagnetic resonance (EPR), refers to the phenomenon that a resonance transition between magnetic energy levels occurs when the electron spin magnetic moment is impacted by an electromagnetic wave of specified frequency in a magnetic field. This phenomenon can be observed in paramagnetic substances with unpaired spin magnetic moment (i.e. compounds containing unpaired electrons). Thus, electron spin resonance is an important method to reveal the microstructure of a substance by probing the unpaired electrons in the material and analyzing how they interact with surrounding atoms. This method has high sensitivity and resolution, and it is a nondestructive detection technique for analyzing the internal structure of materials. This technique has been widely used in physics, chemistry, biology and medicine, and other fields of study.
This apparatus of electron spin resonance in microwave band is specially designed for teaching advanced physics at universities and colleges. The instruction manual contains comprehensive materials including experimental configurations, principles and step-by-step instructions. Please click Experiment Theory and Contents to find more information about this apparatus.Using this apparatus, the following experiments can be conducted:
1. Study and acknowledge electron spin resonance phenomenon.
2. Measure Lande's g-factor of DPPH specimen.
3. Learn how to use microwave devices in EPR system.
4. Understand standing wave by changing resonant cavity length and determine waveguide wavelength.
5. Measure standing wave field distribution in resonant cavity and determine waveguide wavelength.
Specifications
| Microwave System | |
| Short-circuit piston | adjustment range: 30 mm |
| Specimen | DPPH powder in tube (dimensions: Φ2×6 mm) |
| Microwave frequency meter | measurement range: 8.6 GHz ~ 9.6 GHz |
| Waveguide dimensions | inner: 22.86 mm × 10.16 mm (EIA: WR90 or IEC: R100) |
| Electromagnet | |
| Input voltage and accuracy | Max: ≥ 20 V, 1% ± 1 digit |
| Input current range and accuracy | 0 ~ 2.5 A, 1% ± 1 digit |
| Stability | ≤ 1x10-3+5 mA |
| Strength of magnetic field | 0 ~ 450 mT |
| Dimensions | 140 mm (diameter) x 270 mm (height) |
| Pole spacing | ~ 20 mm |
| Sweep Field | |
| Output voltage | ≥ 6 V |
| Output current range | 0.2 ~ 0.7 A |
| Phase adjustment range | ≥ 180° |
| Scan output | BNC connector, saw-tooth wave output 1~10 V |
| Solid State Microwave Signal Source | |
| Frequency | 8.6 ~ 9.6 GHz |
| Frequency drift | ≤ ± 5×10-4/15 min |
| Working voltage | ~ 12 VDC |
| Output power | > 20 mW under equal amplitude mode |
Operation mode & parameters | Equal amplitude |
Internal square-wave modulation Repetition frequency: 1000 Hz Accuracy: ± 15% Skewness: < ± 20％ | |
| Voltage standing wave ratio | < 1.2 |
| Waveguide dimensions | inner: 22.86 mm × 10.16 mm (EIA: WR90 or IEC: R100) |
Parts List
| Description | Qty |
| Main Controller | 1 |
| Electromagnet | 1 |
| Support Base | 3 |
| Microwave System | 1 set (including various microwave components, source, detector, etc) |
| DPPH Sample | 1 |
| Cable | 7 |
| Instructional Manual | 1 |
Diagram of apparatus
(Click figure to enlarge)
(c)
Waveform of EPR signal
(Click photo to enlarge)
Standing wave distribution in cavity
(Click figure to enlarge)
