Related Experiment Video
Updated: Apr 21, 2026
11:30
Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity
Published on: March 6, 2017
11.1K
Spectral properties of microwave graphs with local absorption
Markus Allgaier1, Stefan Gehler1, Sonja Barkhofen1
1Fachbereich Physik der Philipps-Universität Marburg, D-35032 Marburg, Germany.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|October 30, 2014
Summary
This study experimentally investigated microwave graphs, finding that absorption affects spectral properties. Introducing absorption at vertices and bonds revealed how it influences level-spacing and length spectra, particularly for specific orbital paths.
Area of Science:
- Quantum Chaos and Statistical Mechanics
- Microwave Network Analysis
- Condensed Matter Physics
Background:
- Understanding the impact of absorption on spectral properties of complex systems is crucial.
- Previous studies have explored spectral statistics in various physical contexts, but the role of controlled absorption in microwave graphs requires further investigation.
Purpose of the Study:
- To experimentally investigate the influence of absorption on the spectra of microwave graphs.
- To analyze how absorption, introduced at different locations (vertices and bonds), affects level-spacing and length distributions.
- To compare experimental results with theoretical predictions, specifically a generalization of the Wigner surmise.
Main Methods:
- Construction of microwave networks using coaxial cables and T junctions.
- Introduction of absorption by attaching a 50Ω load to vertices in graphs with and without time-reversal symmetry.
- Introduction of absorption along a bond using a variable microwave attenuator.
- Measurement and analysis of level-spacing distributions and length spectra.
- Comparison of experimental data with theoretical models, including the Poli et al. generalization of the Wigner surmise.
Main Results:
- Good agreement was found between experimental level-spacing distributions and the generalized Wigner surmise using an effective coupling parameter when absorption was introduced at vertices.
- Peak heights in length spectra corresponding to orbits avoiding the absorber remained independent of attenuation.
- Peak heights for orbits traversing the absorber once or twice decreased as expected with increasing attenuation.
Conclusions:
- Absorption significantly influences the spectral properties of microwave graphs.
- The study validates theoretical predictions for absorption effects in specific graph configurations.
- The findings provide insights into the interplay between absorption, graph topology, and spectral statistics in complex systems.
More Related Videos
Related Concept Videos
01:14Molecular Spectroscopy: Absorption and Emission
4.1K
Molecules possess discrete energy levels called quantum states. Unlike atoms, which have simpler energy levels, molecules possess additional rotational and vibrational energy levels. Each energy level is separated by an energy gap, with the gaps between adjacent electronic, vibrational, and rotational levels varying significantly. The three types of energy levels in a diatomic molecule are shown in Figure 1.
4.1K
01:19IR Spectrum
3.1K
When infrared (IR) radiation passes through a molecule, the bonds stretch or bend by absorbing the radiation. This absorption creates the molecule's absorption spectrum, which is the plot of its percentage transmittance versus wavenumber.
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0%...
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0%...
3.1K
01:16Spectrophotometry: Introduction
8.4K
Spectrophotometry is the quantitative measurement of the absorption, reflection, diffraction, or transmission of electromagnetic radiation through a material as a function of the intensity and wavelength of the radiation. A spectrophotometer is a device used to measure the change in the radiation intensity caused by its interaction with the material.
The essential components of a spectrophotometer include a source of electromagnetic radiation, a slot for placing a material to be analyzed, and a...
The essential components of a spectrophotometer include a source of electromagnetic radiation, a slot for placing a material to be analyzed, and a...
8.4K
01:30UV–Vis Spectrum
3.0K
When light passes through a substance, a portion of the light is absorbed while the remaining light is reflected or transmitted. If the molecule absorbs light between the wavelengths of 180–400 nm range, the UV spectrum is obtained, and if it absorbs light in the 400–780 nm wavelength range, the visible spectrum is obtained.
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar...
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar...
3.0K
01:32UV–Vis Spectroscopy of Conjugated Systems
5.8K
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is...
One of the factors influencing λmax is...
5.8K
01:03IR Frequency Region: Fingerprint Region
2.0K
IR spectra are divided into two main regions: the diagnostic region and the fingerprint region. The diagnostic region of the spectrum lies above 1500 cm−1. The absorptions resulting from single-bond vibrations of the N–H, C–H, and O–H stretch at higher wavenumbers and appear on the left side of the spectrum. The stretching absorptions of the C≡C and C≡N occur between 2100–2300 cm−1. In contrast, those arising from stretching absorptions of the...
2.0K