Spectroscopy Definition and 305 Threads

I have a question about energy reconstruction. I'm writing up a paper, and I'm trying to understand why this is the reason, before putting it in my paper. I know from experimental evidence that it is the case, though I would like to know if there is a reason. Let's say you have a sufficiently...

Hi guys, So my project partner and I are struggling to solve a problem with our laser spectroscopy data for rubidium isotopes and I thought it may be a good idea to see if you could help us. If you take a look at the attached image you will see that the blue line shows our doppler free...

Dear friends I have a question regarding to polarized Raman spectroscopy. When we are talking about parallel and perpendicular electric field of the laser, is the magic angle 90° or 54.7°? I'd be grateful if you could answer me as soon as possible. Best wishes Kasra

I am looking for an alpha detector to do an alpha spectroscopy (and maybe beta as well). The rough setup is a vacuum tube with a detector in one end and a source in the other, possibly with a magnet in the middle. I have googled around, but my problem is that I don't really know what is...

Hi all, I'm relatively new to the forum, but excited to be a part of a community discussing physics, as I lack company to really discuss my research at my place of work (university), as I am a physicist working solely amongst chemical engineers. I am using a UV-Vis spectrometer, with the...

Homework Statement Hi. I'm starting to read about IR spectroscopy and I have a question. I know that there are 2 kinds of vibrational modes in molecules: bending and stretching, so in a molecule like water for example, how can I tell which one of the vibrational does it have? What I mean...

Hello, I'm currently a sophomore in high school and am interested in working on something to find methods of completely non-invasive toxin detection which I don't see out right now. I've noted that this is done by interpreting the spectra of different materials which could contain the...

Hi there. First time PF poster. I have a question about interpreting IR spectro graphs. I get the general idea of interpreting the sharpness and strength of the line but when I need to ID the pulse down I have to choose between \delta and \upsilon (or mabe its just v) version of the...

1. In a photoelectron spectroscopy experiment Ar is ionised, i.e. an electron is removed from one of the single electron orbitals into the vacuum. An Ar+ ion remains behind. Write down all possible electron configurations and corresponding terms of the resulting Ar+ ion (assuming that the...

Hello, My problem is as follows: The lab I am working on requires the construction of a calibration curve from the measured absorbance of samples of known phenol concentration to intrapolate the phenol concentration of two unknown samples. I have constructed the calibration curve and...

What is the difference between raman-spectroscopy and usual spectroscopy?

Hi! I'm a little confused about simple spectroscopy. In typical absorption experiments, we scan the laser frequency w and get a anti-peak/dip in the transmitted intensity I(w) around a resonance frequency. The size of the dip, i.e. the population of the excited level, usually depends linearly on...

I made some frequency calculations in Gaussian (using various method/basis set combos) and I have to find which method/basis set combo is the most accurate by comparing the results to literature values. I got the calculated wavenumbers along with their intensities but my professor tells me I...

I was thinking of preparing applesauce for some type of spectroscopy( ex: Raman). I was thinking of testing it for arsenic. Does anyone have any idea what applesauce would dissolve in ( I realize this is more of a biology question). thanks

is it true to say that any molecule having a centre of symmetry will have the symmetric stretching IR inactive? thanks!

I have asked a question about this before but this is a different question. The experiment that my lab partner and I performed used a 360 degree rotating assembly which had the light source (Hydrogen and Sodium) and the telescope at opposite ends while the diffraction grating sat in the...

I am a chemistry student and would like to know how to identify the g(parallell) and g(perpendicular peaks in the ESR spectra of copper(II) complexes.

Hi, I have finished an experiment about vibronic transitions for the N_2 molecule and I'd like to compare my results ( vibrational frequencies and dissociation energies of the electronic states interested in the N_2 second positive and N+_2 first negative band systems ) with the accepted...

I have been conducting liquid phase adsorption experiments of xylene and toluene using activated carbon. I made solutions at 2 concentrations (200ppm and 400ppm) of individual components of toluene and xylene in methanol, as a solvent. Initially, the plan was to use Gas Chromatography to...

Indicate those of the following statements that are correct for the compound 13CH3OH (The 13 in front of C is supposed to indicate carbon-13) a. The carbon-13 spectrum will be a 1:2:1 triplet. b. The proton NMR spectrum will be a 1:1 doublet and a broad singlet. c. The broad singlet in the...

Hello there! Im studying microwave spectroscopy, and I'm stuck because I don't see why the spacing between rotational energy levels increases as J does. Can anyone explain please? Also, about IR, I see everywhere that the selction rule is Δv=±1. Correct me if I'm wrong but I'm guessing...

Ultrafast laser spectroscopy, as I know, is used for the determination of femtosecond events in condensed phases. My question is, what applications do these discoveries have, or are they just for "research"?

Hi, I'm a computer scientist w/ very little hardware experience. I've been playing with the idea of using NIRS for a brain computer interface. The basic principle is pretty simple: You have a laser diode and a detector that is 2-3 cm away from the diode. Unfortunately I have almost no...

Okay, I'm havin trouble understanding the difference between NMR and spectrums. As far as I know: in NMR you excite a nuclei from one state to another. The frequency of the energy absorbed is what we measure. How is that related to normal spectrums and colour? For example, absorption of...

function: e^-(x^2/2) operator: d^2/dx^2 -x^2 The answer key says the function is an eigenfunction of the operator with an eigenvalue of -6. I can't figure out how to reach this conclusion. Also, Wolfram Alpha says d/dx(d/(dx)e^(-x^2/2)) = e^(-x^2/2) (x^2-1). Isn't this inconsistent with...

I've been looking at spectra from diatomic molecules. If I know the temperature of the material I'm looking at and I know which transition I want to look at how can I calculate what the observed flux (in Jansky) should be? Also, what can I calculate from observed FWHM? Thanks.

Dear PF, I'm a graduate student working in an ultracold atomic phys lab. We're trying to build a new machine with Li6 as one of the components, but in order to cool it we need to do saturation absorption spectroscopy on a separate stand-alone cell in order to tell our lasers what frequencies...

Homework Statement The Raman spectrum of ethene, obtained using 488.0nm radiation from a laser, shows an intense line at 540.0nm. Calculate the wavenumber for this vibration I know that you get stokes, anti-stokes and rayleigh scattering. Not sure how to calculate the wavenumber though ...

Hi! I have two (stupid) questions: 1) We can determine what elements are present in distant stars by studying their spectrum, right? But if the spectrum of some star is redshifted, wouldn't we be fooled into believing some elements to be present there that might not really be there, due to...

Homework Statement Give two reasons why as molecular size increases does it become increasingly difficult to experimentally obtain well-resolved rotational spectra? The Attempt at a Solution Basically I know one reason. The energy levels become more tightly packed. I have another...

For my advanced physics lab course this semester, I recently conducted an experiment using a hyper-pure germanium detector to measure the energy of gamma rays released upon the formation of deuterium (DF). Essentially, I used a neutron source to bombard a hydrogen rich target (used both...

Hello, I am currently in an analytical chemistry course where I am required to write a report on Raman Spectroscopy. The typical description of Raman Spectroscopy is the excitation of an electron to a "virtual" state, whereupon it can relax to a non zero vibrational level in its ground...

In class we learned about the fundamentals behind RBS using a linear accelerator that accelerates He+ ions to 2MeV. We were then provided an example where those ions collided with a sample with layers of Silicon-Bismuth-Silicon, each of known thickness; and, we were then shown the corresponding...

Hi, I am new to this forum but I am an applied physics student and I'm working on a seminar on deep space spectroscopy. My question is actually on the equipment being used for my research. I am using an SBIG ST-7 camera with a DSS-7 spectrograph and I've been running calibration studies with...

Hi, I am currently in the process of writing up my lab reports and wanted to know how to report mass spectroscopy and elemental analysis in the RSC style. In my report guidelines it suggests elemental analysis should be reported as follows: "Shown in the form: Found: C, 63.1; H, 5.4...

The emission spectrum of an unknown element contains two lines - one in the visible portion of the spectrum, and the other, ultraviolet. Based on the electromagnetic spectrum and Neil Bohr's model of the atom, account for the difference in energy between these two lines. I'm having a bit of a...

Anyone know a source for a mathematical analysis relating the slit-size/throughput for a spectrometer vs SNR? I find that I always get better SNR (but not necessarily resolution) with a wider slit or higher throughput monochromator when doing emissions work. Fritz

Homework Statement A Mass-spectrometer consists of cylindrical capacitor with inner radius R1=4.5 cm and outer radius R2=5.1cm. Ions enter the mass-spectrometer through a narrow slit which is situated in between the capacitor plates as shown on the picture. Uniform magnetic field B=0.4 T is...

hey guys, i hope you can help. my task is to analyse data of raman spectroscopy. therefor i have to deconvolute it. that means the data must have been convoluted somewhere. is it true that the raw data which i receive is convoluted already? or is it common to convolute the data "active"...

Kirchhoff's Three Laws of Spectroscopy are as follows. 1. An incandescent solid, liquid, or gas under high pressure, emits a continuous spectrum. 2. A hot gas under low pressure emits a "bright-line" or emission-line spectrum. 3. A continuous spectrum source viewed through a cool, low-density...

I've been doing IR spectroscopy to examine to the absorption spectrum of water and carbon dioxide, after which I took another absorption spectrum with a methane gas cell. The absorption spectrum without the methane shows absorption from carbon dioxide around 4000nm, however, this is not apparent...

Hi Does anybody know of any good papers/texts explaining this concept? I am mainly looking for two-pulse RS. Niles.

Hi, could someone tell me how the fine edge structure next the the absorbing edge in an XAS arises? from my understanding an XAS is a plot of absorption coefficient against energy of incoming xray. The absorption edge is at an energy corresponding to when the energy is just sufficient to...

Homework Statement Why does chromium(III) absorb light? Explain what is happening on an atomic level. -> I don't really get this problem. Can you help me out...? Please... Homework Equations The Attempt at a Solution

Im trying to solve back for Jupiters effect on the suns orbital velocity. I've looked up the asnwer and its 12.7 m/s and the formula I have for this is http://en.wikipedia.org/wiki/Doppler_spectroscopy v = SQR (Gm*/r) where G is Grav constant M is the mass of the star (planets mass is...

Homework Statement When detecting alpha decay with a spectrometer, why is it important to evacuate the chamber to create a adequate vacuum for where the source is place? Why is it better to place a radioactive source underneath a detector facing up rather than above the detector and facing...

Homework Statement I've recorded an extract of a radio podcast (from Chemistry World) which deals about spectroscopy. But there are a few points missing in my transcription (I'm French) Here it is : http://vfsilesieux.free.fr/spectroscopyaudio/audio.swf I have called (1) to (6) the...

I'm currently working on a lab that is exploring the Raman effect. One of the suggested exercises was to record the raman spectrum (from a mercury lamp through CCl4) around the rayleigh peaks at 435.8 nm and 404.7 nm. For the former, my results were fairly consistent with what I expected in that...

Tell me what do the peaks in the graph show which is b/w Intensity and wave number in raman spectroscopy ? Are the peaks due to transition from a grnd state to an exicted state or vice versa , low energy are stokes and high energy are the anti stokes one

Heres the question [PLAIN]http://img213.imageshack.us/img213/2669/16772870.jpg I know that I'm supposed to derive these values from the fact that I know the absorptions of 2 different isotopes of the diatomic molecule but I don't know how to go about doing it. I can obtain the masses of...