Talk:Photodissociation

From Wikipedia, the free encyclopedia

	Physics Portal This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
Stub	This article has been rated as stub-Class on the assessment scale.
Low	This article is on a subject of low importance within physics.
Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.

[edit] Merge from photolysis

This page and photolysis essentially duplicate each other. I think the term Photodissociation is probably the simpler one and hence propose merging to here.--NHSavage 19:49, 8 September 2006 (UTC)

I think both terms are not equal, in the sense that photolysis describes a process of a more industrious nature. Photodissociation is certainly the term used in astronomy, which is described in this page. I therefore support this proposal. Errabee 20:07, 8 September 2006 (UTC)

done.--NHSavage 18:24, 11 September 2006 (UTC)

Can someone REVERT the MERGE ? they are two separate articles : In contrast to fotolyses only 1 molecul is broken down in fotodissociation. (from the NL version) reg. Mion 01:52, 7 October 2006 (UTC)

I believe that the NL article is wrong. I have always seen the two terms used as having the same meaning. Also the quote you give does not make any sense to me. How can more than one molecule be broken down by a photon? If I am wrong please find a reference to show it (ideally a standard university textbook). Meanwhile I will try and find one which says the two are the same. Even if there is a subtle difference in the correct use of the two terms (and I may have been using the two as synonyms incorrectly for a decade) I would still argue that the two articles should remain merged as there is not sufficient content to justify two seperate articles on the same topic. --NHSavage 07:28, 7 October 2006 (UTC)

An example of the two terms being used as synonmys is here. This is part of web article on atmospheric chemistry by Chris McLinden who has been working on electromagnetic radiation in the atmosphere for a long time. I still haven't found a proper reference though.--NHSavage 07:37, 7 October 2006 (UTC)

As the writer of that Dutch sentence, I concur that the two are the same process. I meant to say that there is a subtle difference between the two: in astronomy, the term photodissociation is exclusively used, whereas in biology (photosynthesis) the term photolysis is exclusively used. I never meant to say that more than one molecule could be broken down by the same photon. At the time, it seemed to me (OR!) that photodissociation is a process used when densities are low and photodissociation events are scarce (a chance occurrence on individual molecular basis) whereas photolysis is used in a more industrious context (sort of an assembly line). Errabee 11:08, 7 October 2006 (UTC)

That's fine. In atmospheric chemistry the two terms are used intechangeably in my experience, although most people tend to use photolysis not photodissocaition.--NHSavage 12:04, 7 October 2006 (UTC)

So, one is more common used, and the other is a better description of the process ? . Mion 12:06, 7 October 2006 (UTC)

No, not exactly. The usage depends on the context. In astronomy, photodissociation is used exclusively (in the group in which I was working, we didn't even think about using photolysis); in atmospheric chemistry the term is apparently used interchangeably; and in biology, photolysis is used. That nicely reflects my density theory :) Errabee 12:58, 7 October 2006 (UTC)

You say tom-ay-toe and I say tom-ah-toe. Notably the IUPAC Gold book only has a definition for the term photolysis so that is probably the prefered term for chemistry. Where the actual page is does not matter IMHO as both terms are in the first line and one redirects to the other.--NHSavage 14:11, 7 October 2006 (UTC)

OK, clear enough, thanks. Mion 15:06, 7 October 2006 (UTC)

[edit] Higher energies

As the article on supernovae links to this page, shouldn't it also mention the photodissociation of nuclei?

I have never heard of supernovae photodissociating nuclei. As I have always understood, supernovae are the only way atoms heavier than oxygen can be formed (through fusion). The reverse proces (iron into helium, no less) seems unlikely to me, and I would hesitate to quote that. Disclaimer: I am not an astronomer; I just happened to do some scientific research into an astronomy related subject, and took some courses of astronomy of interest to my field of expertise (which did not include supernovae). Errabee 00:09, 6 October 2006 (UTC)

Actually, the information on Supernovae appears to be incorrect. It is the rebound shockwave that shatters iron atoms into nucleons. That makes it totally unrelated to photodissociation. Errabee 16:39, 6 October 2006 (UTC)