 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Natural Science Forum / Physics / Particle Physics / April 2008Experimentally Determined Rydberg Constant for Hydrogen
Does anyone know where I can find the value of an accurate, experimentally determined Rydberg constant for hydrogen? Thanks, Steve Bell Since there is a one-to-one relationship between hydrogen's Rydberg constant and its ground state binding energy, an accurate, experimentally determined value of hydrogen's ground state binding energy would also be of interest to me. Steve Bell > Does anyone know where I can find the value of an accurate, experimentally > determined Rydberg constant for hydrogen? > > Thanks, > Steve Bell The Particle Data Group's "Particle Physics Booklet" gives a value 13.6056923(12) eV (the digits in parens are the uncertainty in the last 2 digits given). They usually give experimental references -- look in http://pdg.lbl.gov Tom Roberts > Since there is a one-to-one relationship between hydrogen's Rydberg constant > and its ground state binding energy, an accurate, experimentally determined [quoted text clipped - 8 lines] >> Thanks, >> Steve Bell Hi Tom, Thanks for the information. This value, when converted to a Rydberg constant, looks like it gives R_inf. I'm looking for R_H, specifically an accurate experimentally determined value for R_H. I don't think the 13.6056923 could be an true, "uncorrupted by theory" experimental value, since an experimental value should show only real world effects, that is, it should have "in it" the effect of finite nuclear mass. R_inf and its associated binding energy does not, so it's difficult for me to accept the 13.6056923 value as truthfully what hydrogen itself "presents" to the outside world. Steve > The Particle Data Group's "Particle Physics Booklet" gives a value > 13.6056923(12) eV (the digits in parens are the uncertainty in the last [quoted text clipped - 15 lines] > >> Thanks, > >> Steve Bell > Thanks for the information. This value, when converted to a Rydberg > constant, looks like it gives R_inf. I'm looking for R_H, specifically an [quoted text clipped - 5 lines] > 13.6056923 value as truthfully what hydrogen itself "presents" to the > outside world. The booklet calls this "Rydberg energy" and has a formula h*c*R_\infinity = m_e*c^2*alpha^2/2. That clearly has nothing related to the nucleus or proton in it, and it looks like a theoretical formula based on experimental measurements of the constants involved rather than direct measurements on hydrogen (though I believe those are involved in measurements of \alpha). I am not familiar with the distinction you make, I'm just reading the booklet and passing on its contents. But look it up, as the PDG usually provides references for their data. Tom Roberts > Steve > [quoted text clipped - 21 lines] >>>> Thanks, >>>> Steve Bell Hi Tom, The way the proton comes in, is to replace m_e, the rest mass of the electron, with its reduced rest mass, which does involve the rest mass of the proton. If that is done, values different than 13.5056923 eV and its corresponding R_infinity are obtained. You have confirmed that the value 13.6056923 does not give R_H, but R_infinity. It sure looks hard to find an accurate, "purely experimentally determined" (i.e., not derived by an equation) Rydberg constant for hydrogen (R_H) on the net. I find that rather surprising. The Wikipedia site presents a value: http://en.wikipedia.org/wiki/Rydberg_constant But it's from an equation. Perhaps there is no way to actually directly measure either hydrogen's Rydberg constant or its ground state binding energy. Once again, I would find that surprising. I tried looking at the link you've given, but couldn't find the 13.6056923 number, but that is exactly the number for R_infinity quoted at the above Wikipedia site. The number 10967758.341 m^-1 is given for R_H. I wonder if physicists would say that if indeed, R_H were determined directly from experimentation, this is what would be obtained (with some slight difference, due to the particular experimental error that occurred). Thanks for the information, Steve > > Thanks for the information. This value, when converted to a Rydberg > > constant, looks like it gives R_inf. I'm looking for R_H, specifically an [quoted text clipped - 43 lines] > >>>> Thanks, > >>>> Steve Bell I've also found another link at: http://www.lancs.ac.uk/users/spc/teaching/py301/phys301.htm On page 9 of Part 5, a value of 1.0967759 x 10^-7 m^-1 is given, and it is directly stated "from expt (line spectra)." This is real close to the Wikipedia R_H value. I wonder if physicists would say, then, this is actually the R_H value, and the corresponding binding energy is what hydrogen itself physically binds the electron with in its ground state. Steve > Hi Tom, > [quoted text clipped - 72 lines] > > >>>> Thanks, > > >>>> Steve Bell |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.