Spectroscopy Definition and 305 Threads

I know that theorically the numbers of counts between compton edge and the photopeak must be zero. In practice it doens't occur. Why? Thanks in advance!

Are the results of Atomic Absorption Spectroscopy affected if the metal were ions? For example, if you were trying to measure the amount of zinc in a sample but part of it was dissolved as ions and other parts were simply solid, would they measure the same absorption or would the ions not be...

Homework Statement Calculate the energy and radius for each of the five lowest (n = 1,2,3,4,5) electron orbits in a Helium atom with only one electron. Enter the energy as a positive value in units of "eV" and the radius in units of "nm". Hint: The Helium nucleus has 2 protons so Z = 2 and...

Homework Statement Light in the near-infrared (close to visible red) can penetrate surprisingly far through human tissue, a fact that is being used to "illuminate" the interior of the brain in a noninvasve technique known as near-infrared spectroscopy (NIRS). In this procedure an optical...

Homework Statement I just want to know if there is a relationship between the ground state of Hydrogen which is 13.6 eV and the ground state of Helium. The problem is asking me to find the ground state of Helium, but I am not sure how to go about it. Any advice? Homework Equations...

Homework Statement I have a 3 compounds with the same formula: C6H12O2 I need to find the molecules by interpreting the H NMR spectroscopy http://aceorganic.pearsoncmg.com/epoch-plugin/tempfiles/1867_430.jpg http://aceorganic.pearsoncmg.com/epoch-plugin/tempfiles/1869_524.jpg...

Can anyone explain what "Electron Transmission Spectroscopy" is? Or give a link where I can get an explanation?

Raman spectroscopy of protein please help Hey any Raman experts out there? Im doing Raman spectroscopy of a protein called c-reactive protein (in aquous solution) using 532nm 10mW and the protein placed in a nmr tube. I can nicely get a spectrum of benzene and cyclohexane, but when I am doing...

I read in a journal article that in raman spectroscopy "it is well known that signal yield increases with shorter wavelength". Can anyone please explain why? I would've thought longer wavelengths = shorter frequencies = higher susceptibilities?

I'm trying to comprehend a paper I'm supposed to summarize this one: ---ok it won't let me post urls---- whatever My question, is what is the deal with photoinduced absorption spectroscopy? I gathered that it involves a "pump" (burst of light) striking the sample and then a "probe"...

Hi, I have designed and built my own impedance spectroscopy instrument, using a lock-in amplifier approach, with a reference signal. I know the basic theory behind impedance and impedance spectroscopy. However, I would like some thoughts on experimental set-up. I have a reference source...

Hi I'm trying to measure the concentration of a sample dissolved in water. I'm using the spectrometer USB4000 which directly gives me the absorbance value. Using beer-lambert law is there a way i can determine the unknown sample concentration from this measurement? I have the values 'A' and...

anyone here is good at organic spectroscopy ?? I really need help with NMR spec > < thanks a lot !

I've been trying this for 3 hours and I'm getting nowhere. These are the graphs I made for Hydrogen Intensity vs Frequency for a radio telescope that transits the sun and galactic arms of the galaxy. http://img220.imageshack.us/img220/5904/helpgraphia6.jpg...

Hi Everyone, I am giving a talk on group theory as related to spectroscopy (IR & Raman) and I was curious about how to explain the jump from knowing which modes in the charcter table are Raman active to predicting what kind of vibration they will have. For example the Td point group has raman...

hey everybody, please suggest some good books and online websites for basic concepts of spectroscopy

Homework Statement For a many electron system with L=2,S=1 and J=2 calculate the angle between the L and S vectors both according to the old quantum theory and quantum mechanics. Homework Equations The Attempt at a Solution I suppose this problem is nothing but a simple application...

I referred to hyperphysics to learn that for electric dipole transition,the selection rules are \Delta\ l =\ 1 Or, \Delta\ l =\ -1 And, \Delta\ m_l =\ 0 Does not it include n transition? How is n transition different from transition among the orbitals? I mean n transition...

Is there a way to measure the atomic number of a source using gamma spectroscopy? Like, I know that if you have different back scattering material, it will produced different intensity backscattering peaks, but is there a formula that relates intensity of backscattered peaks to the atomic number?

I have done a few Spectroscopy questions already, However I am having troble with these last three problems. Any help would be GREAT! Here is the link tothe spectroscopy questions. On worksheet 6b, I need help on #1 and #2. On worksheet 6a I need help on #4...

please reference the link here This is the gamma spectrum for Co-60 from the wikipedia site:http://en.wikipedia.org/wiki/Gamma_spectroscopy though wikipedia might not be the best of sources, I was just wondering a few things. The two peaks around channel 700 and 800 are referred to as a...

Hi, I wanted to know that whether my following experiment is conceptually correct or not. I am making a project on spectrosopy. And I have created my files and chart and everything the only thing which is left is a working model. Now what i am trying to do is to find out the...

Hi I have decided to make my chemistry project on spectroscopy. I have included optical spectroscopy,Molecular spectroscopy,Resonance spectroscopy and X ray spectroscopy. Molecular spectroscopy includes microwave,raman,visible,stark,photoelectron and etc I am in the 11th standard ie 16...

[SOLVED] Sites with IR, 1H NMR, 13C NMR, and mass spectroscopy? I was wondering if anyone knew where I can look at IR, 1H NMR, 13C NMR, and mass spectroscopy (sites or programs). I'd like to be able to input the name of an organic compound and be able to see these spectra. Thanks.

Homework Statement For (NO)2+, experiments show 1 Raman active vibrational mode around 1450/cm; 2 strong IR active modes at 2400/cm and 550/cm; and 1 weak IR active mode around 3600/cm. What does that say about its geometry? The Attempt at a Solution Never mind, I think I got it :)

I seek a suitable and current graduate level text on astronomical spectroscopy. The desired emphasis is on stellar sources. I would appreciate recommendations.

I have two monochromatic beams, one green, one red. I combine the beams together and get a single yellow beam. I pass the yellow beam through a spectroscope and determine its spectrum. What do I see? A red band and a green band? A yellow band? I suspect that what I'd see is: A green band...

As I was walking to work yesterday, I thought about how each step I took on the concrete sidewalk spread phonons out in all directions. (Let me know if I'm misusing the term phonons.) Which brought me to the question in the title.

Hello everyone, hope you are all well. I would like to ask a simple spectroscopy question please. "An electron has been excited from the ground state to the 3p state. Find the orbital angular momentum of the electron" This is my interpritation of the question, 3p means n=3 thus...

I'm trying to teach myself the theory behind NMR spectroscopy, but I am having some trouble with some pchem/physics concepts that I have never seen before. The chapter I am currently on talks about the quantization of nuclear angular momentum. What I don't understand is, what is the...

Hello all, I am currently doing a 3rd year Astronomy and Astrophysics course and I am having some trouble with the current problem set (this is mainly because our teacher doesn't really teach us anything but that's another story). This is the question in particular that is bothering me...

I'm doing a project on the Crab Nebula for my first-year astronomy class and I am finding the spectroscopy a bit puzzling. What I have read is that the normal emission line for a particular gas is split into two, one red shifted and one blue shifted. This of course is accounted for by the Dopler...

I have a question which was found on my Pre-lab Q> State the equation that is used to determine the energy content of a packet of light of specific frequency. Tried googling it,but couldn't find the answer.

OK, I have a lab assignment on absorbtion spectra. The nuts and bolts of generating a spectrum are a) pretty clear to me and b) nothing to do with quantum mechanics, but a large part of the assignment is theory on why the spectrum looks the way it does. The sample is vapour of molecular iodine...

Can someone explain why an absorbance maxium is always used for an assay. What problems would occur if an absorbance minimum were used to get an Absorbance spectrum of a solution? thanks.

Discovery of charm quark, ... Pls add more ...

Hello. Where do the peaks observed in gamma spectroscopy come from? May some specific angles for diffraction be a reason?

The intent of this thread (for now) is to introduce the basic theoretic principles of rotational/vibrational spectroscopy, follow this up with a brief sketch of the expermiental techniques and finally zoom in on the experimental and theoretical aspects of a specific technique of recent interest...

A laser in visible is used in Raman spectroscopy and the resultant spectrum is in IR and Microwave region(which means molecular vibrations and rotations are excited), what type of interaction is this that induces these levels? ( I cannot think more than..."To be Raman active molecules should...

Raman spectroscopy is "Single molecule identification" Hi , I heard that the speciality of Raman spectroscopy is "Single molecule identification", it'd be really great if somebody can tell me HOW! because its surely going to be a question in my exam! Thanks in advance.

Hello, I am about to do a summer project on" ultrafast laser spectroscopy". three months left. Now i am an M.Sc.( MS equivalent ) student and I know little about this topic. can anyone provide me with some material for a crash course?

Why is it not possible to obtain a pure vibrational spectrum(IR-spectrum) of a molecule? (vibrational spectrum always contains lines of rotational energies)

I have two Spectroscopy questions from a "lab" I need to answer. From what I know, Mercury doesn't just emmit blue, yellow, and green light, but also a very significant proportion of ultraviolet light. Since you can't see ultraviloet light, they pressurize the bulbs of Hg gas so it shifts the...

Hi, I went to my proff to ask for my master thesis, he told me that you yourself have to do the experimental set-up for EMISSION AND REFLECTION SPECTROSCOPY ,,,but I am not that experienxed, anybody knows is it an easy task or...?

raman spectroscopy! Hi, can anybody please tell what is the speciality of Raman spectroscopy and how it differs from other techniques?? does it have any uniqueness? more info is welcomed! thanks in advance.

In the electron detection using Silicon Detector ,Liquid nitrogen is used to cool the system . why is it used. What is "sweating" which is caused if the detector is not in vaccum,when kept in liq. nitogen Thanking you in advance. :smile:

I am having major trouble trying to figure the concentration of a substance that is given by the AAS. Here's the question: To determine the iron content in a 'Milo' milk drink, a 5ml sample was diluted to 50ml. the absorption of the diluted solution and of several standard solution were...

Howdy, i was wondering is anyone knows how a UV-visible spectroscopy works and how it differs to a double beam scanning spectrophotometer? i know that UV visible spectroscopy needs a radiation source that is passed into a silt and then in a monochromator but how do u know how to...

I've been doing some research on Muon spectroscopy, and am not that far in the physics world yet. I've got kind of a fuzzy picture of what goes on, but could use some help in identifying some key concepts. The information I have been getting is from the following paper Muon-Spin Rotation...

This assignment is based on the structure and properties of atoms and molecules. I have to summarize their findings in a report with the following format: 1st paragraph: a hand sketch with of Ultraviolet spectroscopy components, all components of Ultraviolet spectroscopy, and how it is used...