Recently, the research team of Li Haiyang, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, has used the principle of radio frequency field constrained ion motion to enhance ionization efficiency, and successfully developed a new type of chemical ionization source based on VUV lamps. The results have been published in the American Chemical Society Analytical Chemistry.
The ionization source can realize the ionization of neutral molecules and is one of the core components of detection instruments such as mass spectrometry and ion mobility spectroscopy. In recent years, "soft ionization" has attracted widespread attention due to its low fragmentation and simple spectrum. The single photon ionization source based on the vacuum ultraviolet lamp (VUV) lamp has attracted wide attention because of its small size and low cost. However, the limited luminous flux (1011 photons / second) and lower photon energy (10.6 eV) limit the sensitivity and range of analytes of VUV lamps.
The researchers used the photoelectric effect of vacuum ultraviolet light to generate photoelectrons on the metal electrode, using the electric field to modulate the energy of the photoelectrons to ionize oxygen to obtain reagent ions O2 +, and using O2 + to carry out a charge transfer reaction to ionize the samples to obtain chemical ionization sources. The RF field is applied in the ionization source, and the ion movement path is longer under the RF field, which greatly increases the collision probability of reagent ions and samples, and improves the molecular ion reaction efficiency, thereby obtaining higher ionization efficiency. The experimental results show that compared with the single-photon ionization method, the detection sensitivity of 13 analytes (including aromatic hydrocarbons, chlorinated hydrocarbons, hydrogen sulfide, etc.) is improved by 12-118 times. In addition, O2 + was used as a reagent ion to realize the analysis of organic substances with ionization energy higher than 10.6 eV, such as propane, 1,2-dichloroethane, chloroform and other polychloroalkanes.
The results of this publication are based on the new magnetic field enhanced VUV ionization source (Anal. Chem. 2011,83,8892) and SPI and CI composite ionization source (Anal. Chem. 2011, 83: 5309-16) ) Is another breakthrough.
Vacuum Forming Machine is a simplified version of thermoforming, where a sheet of plastic is heated to a forming temperature, stretched onto a single-surface mold, and forced against the mold by a vacuum. This process can be used to form plastic into permanent objects such as turnpike signs and protective covers. Normally draft angles are present in the design of the mold (a recommended minimum of 3°) to ease removal of the formed plastic part from the mold.
Vacuum Forming Machine
Vacuum Forming Machine,Manual Vacuum Forming Machine,Thick Plastic Sheet Vacuum Forming Machine,Semi Automatic Blister Forming Machine
Hangzhou Xiaoshan Wanfeng Mechanical & Electrical Equipment Factory , https://www.wanfengmachinery.com