Related Concept Videos
01:22Upsampling
Managing signal sampling rates is essential in digital signal processing to maintain signal integrity. A decimated signal, characterized by a reduced frequency range due to its lower sampling rate, can be upsampled by inserting zeros between each sample. This upsampling process expands the original spectrum and introduces repeated spectral replicas at intervals dictated by the new Nyquist frequency. To refine this zero-inserted sequence, it is passed through a lowpass filter with a cutoff...
01:20Design Example: Capacitance Multiplier Circuit
In integrated circuit technology, a capacitance multiplier is often utilized to produce a larger capacitance value when a small physical capacitance falls short. This is achieved by a circuit that multiplies capacitance values by a factor of up to 1000, such that a 10-pF capacitor can replicate the performance of a 100-nF capacitor.
The circuit illustrated in Figure 1 below incorporates two op-amps, with the first operating as a voltage follower and the second acting as an inverting amplifier.
The circuit illustrated in Figure 1 below incorporates two op-amps, with the first operating as a voltage follower and the second acting as an inverting amplifier.
01:21IR Absorption Frequency: Hybridization
Hydrocarbons such as alkanes, alkenes, and alkynes show characteristic C–H stretching absorption bands. These IR stretching frequencies depend on the hybridization of the involved carbon atom and can be explained in terms of the s character of each hybridized atomic orbital.
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that stretch at a...
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that stretch at a...
01:21Polymer Classification: Crystallinity
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
01:29Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...
01:19Crystal Density
The crystal lattice structure of a material allows us to determine how many molecules exist in its unit cell. With this information, alongside the unit-cell parameters - three distance parameters (a, b, c) and three angular parameters (α, β, γ).Density (ρ) = (Z × M) / (a × b × c × NA)where:Z is the number of formula units per unit cellM is the molar mass of the substancea, b, and c are the edge lengths of the unit cellNA is Avogadro’s numberFor a simple cubic lattice, atoms are located only at...
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Updated: Jul 9, 2026
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20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier
Published on: July 12, 2017
Summary
Troger
Area of Science:
- Photochemistry
- Organic Chemistry
- Materials Science
Background:
- Troger's base is a known organic compound.
- Fluorescence is a key optical property with various applications.
- Understanding photophysical properties is crucial for material design.
Purpose of the Study:
- To experimentally investigate the fluorescent characteristics of Troger's base.
- To analyze both one-photon and two-photon excitation fluorescence.
- To explore the influence of molecular structure on fluorescence.
Main Methods:
- Experimental measurement of fluorescence spectra.
- One-photon excitation spectroscopy.
- Two-photon excitation spectroscopy.
Main Results:
- Observed one-photon fluorescence spectrum with a peak at 337 nm (FWHM ~85 nm).
- Identified violet radiation potentially from pi(*) -pi transitions.
- Achieved two-photon-pumped frequency-upconverted fluorescence (wideband emission, main peak at 337 nm).
- Electron donor/acceptor groups enhance two-photon fluorescence.
Conclusions:
- Troger's base exhibits distinct fluorescence properties under one- and two-photon excitation.
- The pi(*) -pi transition is a likely source of its violet fluorescence.
- Molecular modifications with electron-donating or -withdrawing groups can tune its two-photon fluorescence capabilities.