Density Functional Theory Calculations on the Interstellar Formation of Biomolecules

Density functional theory(DFT)is the most versatile electronic structure method used in quantum chemical calculations,and is increasingly applied in astrochemical research.This mini-review provides an overview of the applications of DFT calculations in understanding the chemistry that occurs in star-forming regions.We survey investigations into the formation of biologically relevant compounds such as nucleobases in the interstellar medium,and also cover the formation of both achiral and chiral amino acids,as well as biologically relevant molecules such as sugars,and nitrogen-containing polycyclic aromatic hydrocarbons.Additionally,DFT calculations are used to estimate the potential barriers for chemical reactions in astronomical environments.We conclude by noting several areas that require more research,such as the formation pathways of chiral amino acids,complex sugars,and other biologically important molecules,and the role of environmental factors in the formation of interstellar biomolecules.

Catalytic Role of H I in the Interstellar Synthesis of Complex Organic Molecule

Using quantum chemical calculations,we model the pathways for synthesizing two purine nucleobases,adenine and guanine,in the gas-phase interstellar environment,surrounded by neutral atomic hydrogen(H I).H I is found active in facilitating a series of fundamental proton transfer processes of organic synthesis,including bond formation,cyclization,dehydrogenation,and H migration.The reactive potential barriers were significantly reduced in the alternative pathways created by H I,leading to a remarkable increase in the reaction rate.The presence of H I also lowered the reactive activation temperature from 757.8 K to 131.5–147.0 K,indicating the thermodynamic feasibility of these pathways in star-forming regions where some of the reactants have been astronomically detected.Our findings suggest that H I may serve as an effective catalyst for interstellar organic synthesis.

Side-On transition radiation detector(TRD)based on THGEM

Purpose The characteristic that TR energy is proportional to the Lorentz factor provides a way for energy calibration.The High Energy cosmic-Radiation Detection calorimeter can be calibrated in space by the TRD in the future.Method In order to make the TR signal stand out from the energy loss signal,a new prototype of TRD called Side-On TRD with THGEM has been built.Side-on TRD uses side window incidence and strip readout to reduce the ionization energy registered in the channel where the TR photons are located,which is supposed to improve the detection efficiency of TR.Result and conclusion The Side-On TRD has been tested at CERN SPS and found the experimental results are significant.