Cold cathode

A cold cathode is a cathode that is not electrically heated by a filament. A cathode may be considered "cold" if it emits more electrons than can be supplied by thermionic emission alone. It is used in gas-discharge lamps, such as neon lamps, discharge tubes, and some types of vacuum tube. The other type of cathode is a hot cathode, which is heated by electric current passing through a filament. A cold cathode does not necessarily operate at a low temperature: it is often heated to its operating temperature by other methods, such as the current passing from the cathode into the gas. Cold-cathode devices A cold-cathode vacuum tube does not rely on external heating of an electrode to provide thermionic emission of electrons. Early cold-cathode devices included the Geissler tube and Plucker tube, and early cathode-ray tubes. Study of the phenomena in these devices led to the discovery of the electron. Neon lamps are used both to produce light as indicators and for special-p

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Accelerating photofragmentation UV Spectroscopy–Mass spectrometry fingerprinting for quantification of isomeric peptides

Oleg Boyarkine, Erik Saparbayev, Elizaveta Solovyeva

Identification of isomeric biomolecules remains a challenging analytical problem. A recently developed spectroscopic method that combines UV photofragmentation and mass spectrometry for fingerprinting of cold ions (2D UV-MS), has already demonstrated its high performance in the library-based identification and quantification of different types of biomolecular isomers. The practical use of the method has been hindered by a slow rate of data acquisition, which makes the fingerprinting incompatible with high-throughput analysis and online liquid chromatography (LC) separation. Herein we demonstrate how the use of a few pre-selected wavelengths can accelerate the method by two orders of magnitude without a significant loss of accuracy. As a proof of principle, 2D UV-MS fingerprinting was coupled to online LC separation and tested for quantification of isomeric peptides containing either Asp or isoAsp residues. The relative concentrations of the peptides mixed in solution have been determined, on average, with better than 4% and 6% accuracy for resolving and non-resolving gradients of LC separation, respectively.

2021

PERFORMANCE OF THE PHIN HIGH CHARGE PHOTO INJECTOR

Daniel Egger, Öznur Mete

The high charge PHIN photo injector is studied at CERN as an electron source for the CLIC Test Facility (CTF3) drive beam as an alternative to the present thermionic gun. The objective of PHIN is to demonstrate the feasibility of a laser-based electron source for CLIC. The photo injector operates with a 2.5 cell, 3 GHz RF gun using a Cs2Te photocathode illuminated by UV laser pulses generated by amplifying and frequency quadrupling the signal from a Nd:YLF oscillator running at 1.5GHz. The challenge is to generate a beam structure of 1908 micro bunches with 2.33nC per micro bunch at 1.5GHz leading to a high integrated train charge of 4446nC and nominal beam energy of 5.5MeV with current stability below 1%. In this paper we report and discuss the time resolved transverse and longitudinal beam parameters measurements. The performance of the photo cathodes made at CERN with a peak quantum efficiency of 18 % is shown as well. Laser pointing and amplitude stability results are discussed taking into account correlation between laser and electron beam.

2010

Cold ion spectroscopy for structural identifications of biomolecules

Oleg Boyarkine

Over the last decade, the spectroscopy of cryogenically cold ions iso- lated in the gas phase has been developed as a new tool for structural elucidations of biological molecules. Cooling allows for vibrational resolution in UV and IR spectra of small to midsize peptides, enabling different multi-laser techniques of conformer-specific spectroscopy. In conjunction with quantum chemistry calculations, IR spectra of sin- gle conformers allows for solving their intrinsic geometries. Here, we briefly review some fundamental and technical aspects of the cold- ion spectroscopy (CIS) approach and illustrate its application for pro- tonated peptides, carbohydrates and for non-covalent complexes of biomolecules. The challenges and limitations of CIS in view of its rele- vance to life-science studies are critically assessed. Finally, we discuss and illustrate some approaches of CIS for the analytical identification of biomolecules, in particular the recently developed method of 2D UV-MS fingerprinting, which combines CIS with high-resolution mass spectrometry.

2018

Vacuum tube

A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential diffe

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A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor

Cathode

A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic CCD for Cathode Current Departs. A conventiona

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