Thursday, January 14, 2016
CHEM 418 Nuclear Chemistry, Winter 2016: Lecture 4 Alpha Decay
This lecture discusses alpha decay in radionuclides. Theories on alpha decay are presented. Systematics and energetics involved in alpha decay are presented. The correlation between Q value and decay energy is described. The Geiger Nuttall relationship is provided, described, and utilized in a model for alpha decay. Tunneling is also exploited to described alpha decay, coupling energy and half-life. Gamow calculations are shown to reflect the Geiger Nuttall relationship. Hindered alpha decay is discussed. Hindered alpha decay is employed to described nuclear properties. Hinderance factors are described, along with how they are calculated and where they can be found. Proton and other charged particle emission are presented.
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I really enjoy the lecture 4.
ReplyDeleteWill you post the answer key for those problems at the end of the each lecture?
I sent the lecture 4 pdf quiz as an attachment through email.
Thank you
Answers for PDF quiz 4 are posted.
DeleteTHe questions at the end of the lecture are often the basis of questions that will appear on quizzes. I can provide some general discussion of the questions in the lecture. These questions can also be discussed at office hours.
ReplyDeleteThank you for answering my question.
Deletelecture watched. As PoKi Tse mentioned, it would be nice to have the answers to the end of lecture questions. Quiz 4 is sent through email. Thank you!
ReplyDeleteI will incorporate this into the upcoming lectures.
DeleteSo referencing question 2, the Geiger Nuttall equation tells us that (Half Life) α (1/sqrt(Q)). Or in words, Half life is proportional to the inverse square root of Q.
ReplyDeleteMy question is, when evaluating 1/sqrt(Q). Should be using the kinetic energy of the Alpha particle, say Tα, of the given reaction, instead of Qrxn?
Just wanted to reason out the calculations, thanks
-Faruq
Faruq
DeleteGreat question. The Q value should be used. However since the alpha decay energy is close to the Q value the correlation will also hold.
Awesome thank you Ken.
DeleteQuiz 4 submitted.
Deletereattempted quiz 4 alpha energy decays. I hope my method is correct.
DeleteLecture 4 viewed and PDF quiz 4 submitted via email!
ReplyDeleteLecture viewed, and quiz submitted.
ReplyDeleteI'm excited to learn about beta decay in the next lecture!
thanks for the comment
DeleteQuiz submitted via Canvas email.
ReplyDeletethanks for the PDF quiz.
DeleteI have finished the lecture and have sent the quiz through the Canvas email.
ReplyDeletethanks!
DeleteQuiz submitted via email
ReplyDelete-Raghav kumar
thanks for the PDF quiz
DeleteI have emailed you my PDF quiz.
ReplyDelete-Shiva
Also for question 4, was there more than one trend for decay by single or double proton emission? The lecture mentioned long half life's, though short half life's was displayed as a possible answer, was that there as a trick?
No trick. You can responds with multiple trends. Three trends were a reasonable response. You can resubmit your quiz if you wish.
DeleteI still only found 2 trends unless you meant the third trend to be " produced from alpha decay" as meaning either :
Delete-following beta decay
-similar to alpha decay
please help clarify I'm still a little confused.
The trends I see for isotopes that decay by proton or double proton emission are:
Deleteneutron poor
light elements, so low Z
short half lives. Some are even listed as "very short"
Please let me know if you need further clarification.
Emailed my quiz.
ReplyDeleteI share a similar question to the student above. In the chart of the nuclides, I saw that a lot of the options given in question 3 had very short half-lives, while the lecture said they had long half-lives.
The proton emission isotopes are indeed short lived. The lecture will be changed to reflect this.
DeleteChange made. Really should have said low probability. In many cases the proton decay half life may be short, but not as short as other available routes. So the half life is long in relative terms. In reality the correct condition is needed to observe proton decay, hence these isotopes are confined to a limited region of the chart of the nuclides.
Delete