新聞動態(tài)2025.06.23?New Measurements and Theory of Mass Independent Isotope Effects and Relation to Archean, Atmosphere and Solar System Origin Using?Quantum Dynamics
? ? ? ? 應林莽研究員邀請，加州大學圣地亞哥分校(UCSD)化學與生物化學系講席講授Mark Thiemens院士?將于6月23日（下周一）訪問我所并在標本樓308會議室做學術報告，歡迎大家參加并積極討論！
? ? ? ? 報告題目：New Measurements and Theory of Mass Independent Isotope Effects and Relation to Archean, Atmosphere and Solar System Origin Using? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Quantum Dynamics
? ? ? ??報 告 人：Mark Thiemens 院士（加州大學圣地亞哥分校）
??? ? ? ? 報告時間：6月23日（周一）上午10:30
??? ? ? ? 報告地點：標本樓308會議室? ??
? ? ?報告人簡介：
? ? ? Mark Thiemens院士是加州大學圣地亞哥分校(UCSD)化學與生物化學系講席講授，曾任UCSD自然科學學部創(chuàng)辦主任(2000-2016)。Thiemens院士主要從事同位素地球化學、大氣化學、宇宙化學等方面的研究，他發(fā)現(xiàn)了化學過程產(chǎn)生的同位素非質(zhì)量依賴分餾效應(MIF) ，開拓了MIF在地球和行星科學的廣泛應用，在多個研究領域發(fā)表了多篇具有影響力的論文，其中Science 22篇、Nature 8篇、PNAS 23篇。Thiemens院士是美國科學院院士和英國皇家學會外籍院士，Goldschmidt獎章(地球化學學會)、Leonard獎章(隕石學會)等國際學會最高榮譽獲得者，AGU、GS、EAG等學會會士，目前是PNAS的地學編委。
? ? ? ? Abstract：? ? ?
The measurement of stable isotopes in natural phenomena dates back to 1947 when an equilibrium isotope exchange model of isotopes was developed by Urey and the stable isotope ratio mass spectrometer was developed by Nier. Since then, the applications have been extensive. The temperature of Earth’s surface is obtained by carbonate oxygen isotopes and polar ice. The rise and fall of polar ice may be determined for the Earth. The temperature of rock formations between minerals was also an early application. Gravity effects on the escape of nitrogen and argon isotopes from the Martian atmosphere have allowed models to be created. Kinetic effects in biological systems have covered many topics, ranging from global primary productivity to metabolic process definitions.
? ?A new class of isotope effects not reliant upon mass were discovered and explored by Thiemens and include photochemistry effects in the atmosphere, origin of the solar system, and, using sulfur isotopes many groups have developed understanding of the origin and evolution of life. A limit in our ability to model these systems at high resolution is that we do not know the isotope fractionation of photodissociation as a function of energy.?The effects are in the UV range, and it is impossible to measure across the spectrum because one needs a synchrotron, and it requires a day for a single measurement. What is needed is a theory that allows one to calculate these effects. In this talk, new applications of quantum effects that have never been included before are discussed and the theory and measurements are shown.
