20xx放射化學(xué)第4講(放射性)-文庫吧資料
2025-07-30 05:47本頁面
【正文】 原子中的結(jié)合能 2022/8/21 Auger electrons(俄歇電子 ) K俘獲過程的另一種伴隨粒子是俄歇電子：當(dāng)一個 L層電子跳到 K層來填充空位時 ， 可以不發(fā)射 X射線 ， 而把能量交給另一個 L電子 ， 于是這個 L電子就會克服結(jié)合能而飛出 。 2022/8/21 b衰變類型 ?b ??? ??? )(1 eYX AZAZb衰變： ?b ??? ??? )(1 eYX AZAZb+衰變 軌道電子俘獲： ???? ?? YeX AZAZ 12022/8/21 b衰變的本質(zhì) b+衰變： p?n+b+(e+)+? b衰變： ?b ??? ?? )( epn軌道電子俘獲： p+e?n+? 2022/8/21 Negatron Decay )(1 g?b b ????? ??? QYX AZAZYQXYXAAAA),()(bbb??222)],1(),([}])1(),1([]),({[]),1(),([cAZMAZMcmmmZAZmZmAZmcmAZmAZmQeeeee????????????????bQb0, M(Z,A)?M(Z+1,A) 2022/8/21 Negatron Decay 1 4 .3 d T321632151 3 8. 4dT903990382121 βSP βYSr??????????vepn ??? ?2022/8/21 Negatron Decay ? A simple decay scheme（衰變綱圖） XAZParent Daughter YAZ 1?Figure Decay scheme for a radionuclide undergoing negatron decay. Two b decay paths are shown. A g ray is emitted from an excited state of the daughter in one decay path. XAZXAZ2022/8/21 Beta Decay（衰變能譜） Figure Energy spectra for negatrons and positrons in b decay. Each spectrum has a maximum b energy, Emax, which corresponds to the energy of the specific transition, corrected for recoil energy imparted to the daughter nuclide. The average negatron energy is approximately onethird of Emax, while the average positron energy is somewhat larger. between bdecay Energy Spectra Difference adecay adecay bdecay 2022/8/21 Negatron Decay PR P? Pb Pb+P?+PR=0 中微子： ,1933:電中性 、 質(zhì)量接近 0 2022/8/21 Negatron Decay ?The continuous bparticle spectrum could be explained by assuming that, in a decay, the antineutrino and bparticle each carry off part of the total energy of the nuclear transition and momentum is also conserved: ?Etrans=Enegatron+Eantineutrino+Erecoil 2022/8/21 Positron Decay bg?b QYXAZAZ ??????? )(1Qb=(mXmYme)c2, M=m+Zme Qb=[MXZmeMY+(Z1)meme]c2 =(MXMY2me)c2 Qb0, MXMY2me 2022/8/21 Positron Decay m i n 2 0. 3 T1151166 221022111 / 21 / 2 βCC βNeNa???????????? a2022/8/21 Positron Decay ?b+衰變主要發(fā)生在富含質(zhì)子的核素中 (., the N/Z ratio is small). ?只有在母體和子體的原子量值差大于 的情況下才能發(fā)生 b+衰變（ ?2=） . 2022/8/21 軌道電子俘獲 2022/8/21 Electron Capture (電子俘獲 ) ? 原子核從核外的電子殼層中俘獲一個軌道電子的過程稱作軌道電子俘獲。 ?發(fā)射的 b粒子的能量最大為幾個 MeV。（ Electron capture decay (EC
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