Spectra Definition and 285 Threads

How can you read the phase spectra from a Fourier Transform? if g(t) = Sin(2\pi f_{c}t) then for the single sided spectrum, you have one frequency component at f=f_{c} with a height of \frac{1}{j} which from looking at the complex plane, corresponds to a phase of \frac{\pi }{2} (ie. g(t) =...

Hello everyone! I bought a Spectra Optics telescope 1400X150 (reflector) for 260 Euro a few days ago and I had quite big expectations on it. The including oculars was on 25mm and 6.5 mm. But when I was going to look at Jupiter recently, then I didn't get a more visible view than a little dot and...

Explain how data from emissions spectra provide evidence for discreet energy levels within the atom?

Homework Statement I'm just curious to if I have answered this questions properly, and was wondering if someone can see if I should add more to what I have written, or completely change my answer. I'm pretty confident with what I've answered, but would like someone to check :) So to begin...

Hi all How can I plot bremsstrahlung energy spectra?What is the formula for this topic? Pleas help me! thanks a lot.

Hi, I don't quite understand which are the fundamental processes for production of photons that are emitted by a "black body". Usually this is explained by considering a cavity in thermodynamic equilibrium but I am not interested in this. I am looking for a more practical description of this...

Hi, I'm hoping someone can advise me on the best place to find the absorption spectra for water (fresh) and ice, for the wavelength range UV to IR. Also, I'm looking for the solar radiation spectrum at the surface of the Earth (i.e. after atmospheric effects have been taken into account)...

Do \bar{H} annihilation spectra vary with element? If \bar{H} collides (slowly, at 10 Kelvin for example) with H, Beryllium, Lead, does it make a difference?

Hi all, I'm just wondering why pure metals, whatever kinds, do not have Raman peaks. Because the visible light cannot penetrate the metals? If so, what kind of EM wave can penetrate metals? Just need some key words for further information. Of course, I would appreciate if you would explain...

I've been looking everywhere for information on the absorption spectra of molecular hydrogen. I need some pretty exact numbers. If anybody can point me in the right direction it would be greatly appreciated.

Can anybody tell me the significance of the band origin for a P(Q)R structure in the ultraviolet region of a molecules spectrum? In standard vibrational spectra, I understand that its roughly the harmonic frequency of the oscillator, and that the rotational constant can also be found from...

Which occurence requires a higher energy? I don't know much about these but for continous, I think the x-ray is able to get close to the nucleus without interacting with the electrons, is then deflected or stopped by the nucleus and the emitted photon can have a range of energies - 0 to Kemax...

What spectra do these closest resemble? I can't seem to find any matches. Thanks in advance!

Homework Statement A transmission diffraction grating with 528 lines/mm is used to study the line spectrum of the light produced by a hydrogen discharge tube. The grating is 1.3m from the source (behind a hole in the center of a meter stick). An observer sees the first-order red line at a...

As we look to the spectra of stars from O to M type, we see that as temprature decreses, the spectral lines become more crowded. Why M-stars have more various elements than O-stars? Is that because of mass or age or what?

Hello, When electron is excited in single atom hydrogen, it jumps to a certain level, let's say from 1 to 4. My question here is, does this electron jump back immediately to 1 or does it cascade itself down to 3 to 2 to 1. and emits 3 lines instead of just 1. Thanks

Is it possible to have an infinite value for the amplitude of a Fourier coefficient? The signal is sin(w0t) from 0 to T/2. My resulting coefficient formula was Fn = 2/[4pi(1-n)] + 2/[4pi(1+n)] so for F1 i got infinity ... is this possible? or is coefficient just wrong?

Im just trying to figure something out here. Iv been working on some spectra stuff. Now, when I look at a gas, I see the spectra, but if I turn up the intesnsity, new lines appear? Where do these lines come from, as I am looking at the same game, just turned up intensity?

Hi, If T is a bounded linear operator on a Hilbert space, what can we say about the spectra of T and T* (\sigma(T)=\{\lambda:T-\lambda I is not invertible})?

An atom has energy levels En=-\frac{A}{n^2} where n is an integer and A is a constant. Among the spectral lines that the atom can absorb at room temperature are two adjacent lines with wavelengths 97.5 nm and 102.8 nm. Find the value of the constant A in electron volts. Initially I thought we...

I know that the selection rule is : \DeltaJ = +/- 1 but our prof said that according to some quantum mechanical calculations the odd values of J are not allowed. So, the allowed transitions are : J 0 <-> 1 ; 2 <-> 3 ; 4 <-> 5... as...

I have been wondering how to realize the color of a mineral by having the absorption Spectra... The following case is an example; The image is the absorption spectra of a Bolivian Amethyst which looks like this; [PLAIN]http://www.tequilabay.com/amethyst300lbbolivian.jpg I have tried...

I read that each line on a line spectra for an element represents an energy level. Hydrogen only has 1 electron which is in the first energy level so why are there so many lines on the H line spectrum?

Hi Does anyone know why acetic anhydride has 2 IR bands at 1760 and 1820? If you look it up in a table it says they are due to the 2 carbonyl groups in an anhydride. But this is what I want to know: 1) What specifically is causing the peaks? Is it asymmetric stretching of the carbonyl...

Is this method good for analyzing a pulse? Why is the averaging of the spectra good for noise cleaning? What's the criteria for defining how much windows in a set of data one should take? Anyone who clarifies this has a big thanks from me.

I have several electronic spectra for different cobalt complexes which I need to analyse. I am fine with finding \lambdamax and the molar absorption coefficient etc. However it also asks me to mark absorption bands on the printout and tabulate \lambdamax values and absorbance values for these...

in an experiment we looked through the diffraction grating to see the spectrum made by a helium lamp. we measured the distance along the meter stick to the point where we saw each color. based on that distance how would you calculate the wavelength of the light that was seen? would you...

what is the basic difference between the spectra obtained through prism and grating?

Merging of overlapped XPS spectra with CASA ( tech. Help needed ) Does anybody knows ways ( options ) to merge two ( or more ) overlapping XPS spectra onto one ( extended ). See graphical example attached. Two optional exp. recoding need to be assumed. 1. "x" scale grid in overlapping...

Homework Statement Determine the chemical shift, integrated intensity, proton type, multiplicity, J (Hz), and # of protons on the adjacent atoms for this spectra given a 400 MHz NMR. http://img411.imageshack.us/img411/7629/chem262lnmr1.png Homework Equations (n+1) rule? (n+1) x...

1. Compare and interpret the infared spectra of 4-methylcyclohexene and 4-methylcyclohexanol. 2. Identify the C-H out-of-plane bending vibrations in the infared spectrum of 4-methylcyclohexene. What structural information can be obtained from these bands?

[b]1. The emission line of He II at 468.6 nm corresponds to what electronic transition? [b]2. I know that the formula 1 / λ = R(1 / nb2 - 1/ na2) may be useful but I'm not sure how the Rydberg's constant would change since it's helium. Also, I'm not sure what to assume as the initial energy...

Can someone explain what "hardening" of a neutron spectra means?

Happy New Year to all you Physics Geniuses out there! I have a question concerning how the optical emission spectrum of a gas would be affected by being dissolved in water. I know very little about spectroscopy so please forgive me if this seems like an idiotic question. Let's assume I...

i am now studying the Doppler effect in a thermal atomic gas If an atom travels in velocity v along x direction at some time, it emits a photon in some direction the momentum of the emitted photon can be well approximated with the free one thus the momentum of the atom after the...

i am now studying the Doppler effect in a thermal atomic gas If an atom travels in velocity v along x direction at some time, it emits a photon in some direction the momentum of the emitted photon can be well approximated with the free one thus the momentum of the atom after the...

I am given 2 mass spectra of protein fragments and don't get how to analysis a mass spectrum of a protein and find Z value with the given m/z ratios. do i take the mass of the whole protein and divide by the m/z on the spectrum to find z? thanks

Hey all, I have a lab coming up that deals with the emission spectra of H, He,Ne,Hg, and N_2 I am looking around for some sources to compare my results to, and I thought I would post here in case anyone knows of a good (preferably online) journal article or reputable website that would...

Homework Statement The following elements should have optical spectra similar to either a hydrogen atom or a helium atom. Indicate which of the following elements should have optical spectra similar to a helium atom. (Select all that apply.) The choices are: Cadmium, Lithium, Technetium...

Hi, This must be a textbook question but I couldn't find exact definitions(quantitative) of these measurements Extinction spectra: Absorption spectra: Transmission spectra: eg. Lets say electric field spectrum of some location/surface is calculated by illuminating a source with and without the...

Homework Statement A line of wavelength 1093 nm is observed in the hydrogen spectrum. Identify the transition that leads to this line. Homework Equations where n refers to the upper state and n' to the lower state. 1/lamda = R (1/n' - 1/n) -----1 Ei - Ef = hc/lamda ------2...

I am a newbie to the forum and impressed by the breadth and depth of the material here. After searching I am unable to answer a question that I have been pondering. One of my brightest students asked whether electrons other than the valence electrons were involved in the emission spectra of...

Homework Statement Hi, I'm having a bit of trouble explaining this physics phenomenon: A sodium lamp emits yellow light; that to the human eye appears to be quite similar to a candle flame in colour. When light from these two sources is viewed through a spectroscope, it is found that...

Homework Statement What are some differences between the spectrum observed for light from the incandescent bulb, the fluorescent tube, and the spectrum observed from sunlight? The Attempt at a Solution I think that sunlight produces an absorption spectrum, whereas both incandescent bulb...

If you're reading a graph of absorption coefficient(cm^-1) versus wavelength(nm), how can you dtermine if the solution is optically dilute? What about optically thick? Thanks Ben

Why don’t emission and absorption properties of an atom cancel out such that no such spectral lines are seen. If electrons in atoms are excited from level 1 to level 2 and absorb energy at some specific frequency, why don’t they then emit that same frequency when they fall back down to level1...

hello, i've Spectra(set of data points) and i need to identify the peaks of the spectra. are there any algorithms for that ?

Hello PF readers, I've got trouble in finding neat examples of spectra of various stellar objects including quasars. Are there any sources of information that I could look for?(I would prefer to get the images of the spectra) I would use the examples of spectra to identify certain stellar...

Can anyone tell me how can I take the impedance spectra of a dye-sensitized solar cell ? Do I need to irradiate (i.e. AM 1.5, 100 mW/cm2) the solar cell during impedance measurement? or I can measure the spectra without irradiating light ? More specifically, how can I get the comparison between...

I have two spectra of a star across the visible and NIR. One spectrum comes from an online resource (CALSPEC) for spectrophotometric standards, and it provides a wavelength array along with a corresponding array of flux values (in units of ergs s-1 cm-2 Å-1) The second spectrum is the...