Spectrum Definition and 725 Threads

My question is, when extracting the count rate from a particular peak in the energy dispersive spectrum (e.g. X-ray fluorescence) Is this done by simply drawing a straight horizontal line from the top of the peak to the y-axis and the corresponding intercept will be the count rate? What if the...

Hi all, I have 2 questions related to the blackbody spectrum. 1 - If a blackbody emits (and absorbs) energy at all wavelengths equally, why does the spectrum look the way it does (i.e. why does it peak in intensity at a given wavelength?) 2 - The fact that the cosmic background radiation...

Homework Statement Hydrogen atom with ionisation energy 13.6 eV is found to have an emission spectrum with lines at 1.89 eV, 10.20 eV and 12.09 eV. Draw a labelled diagram to show the energy levels of hydrogen atom by showing the transitions of electrons causing the emission of the lines...

Hello, I'v been taking an interest to astronomical spectroscopy lately and I have some questions about that. In order to get myself going I wanted to get as much information about Sirius A and Sirius B using the distance, obtained by using parallax(I didn't do that but imagine I did) , and...

Homework Statement What is the cause for the bump in the lower energies of this spectrum: http://en.wikipedia.org/wiki/File:Gammaspektrum_Uranerz.jpg The Attempt at a Solution Is it just normal Compton? I'm doubting that because that is very asymmetric. I can't find anything in any textbook I...

Homework Statement The question says for the hamiltonian \hat{}H+\hat{}H1 calculate the complete energy eigenvalue spectrum. for the ground state show that the result agrees with the one found by the perturbation theory previously. I'd assume \hat{}H here is just the standard...

Hi, I'm looking for papers and general or specific information about the topic Astronomy in UV and X-ray Spectrum. Other than Wikipedia and Google sources, I would be interested in understanding the optical spectrum range and its limits, with respect to the materials used in this astronomy...

shining white light through a gas of a vapourised element causes absorbtion lines to be created in the white light spectrum ie. there are dark lines running through the otherwise continuous spectrum and the position of these lines are unique to particular element. Why is it though that we...

Homework Statement Not really a homework question, but related none the less. I'm confused about what exactly the amplitude spectrum is. As well as the power spectrum. Homework Equations Not really taking a purely mathematical approach here, I'm using numpy for python. Specifically the fft...

Hi guys, I am eager to find out about our spectrum usage. Cause I am working on LTE and it uses either 2.7 GHz or 900 MHz, range of UHF. Do anyone have a link, paper or book referring to various applications spectrum usage, like all other mobile communication or defense spectrum usage. Thank...

If light is quantized, and is given out in packets, why are the EM wave spectrum and the black body spectrum continuous? I am very confused, can someone offer some explanation? Any input is greatly appreciated.

Hi! I am new to these, and off the bat am confused by the units. Manufacturers quote resolution either in units of length, e.g. 0.04 nm, or HZ. For example, 0.04 pm / 5MHz 0.16 pm / 20 MHz 0.8 pm / 100 MHz. I am thrown by this since I thought frequency was the inverse of...

Looking at a HCl spectrum (from hyerphysics: http://hyperphysics.phy-astr.gsu.edu/hbase/molecule/vibrot.html), I don't understand why there is a gap in the middle of the spectrum that seems to act as a line of symmetry in the x-axis. Can anyone help please?

Can someone give a clear definition of what we mean when we say the CMb spectrum is adiabatic and what it means for simple infaltionary models?

I am a piano teacher with some very cool, science-minded students. Usually we stick to basic acoustics, and mechanics in terms of piano technique, but yesterday one of them took things in an interesting new direction. . . he described to me how, when he closes his eyes and listens to the music...

I was glad to see this paper for several reasons. The volume operator in Loop Gravity is the locus of some interesting unresolved questions. The kind that requires and attracts creative mathematicians IMHO. This first paper from Gene Bianchi and Hal Haggard is just a 4-page letter I guess for...

Hello, Over the past few weeks I've been interested in the idea of developing a celestial mass accretion spectrum, or in other words, a spectrum that places celestial objects of a given mass as being part of a band of that spectrum. This spectrum would help give definitions on what a planet is...

I have 3 questions: 1)Does the lines in the spectrum of a star indicate the elements in its surface or also the inner parts? 2)when an electron goes to a higher state, it emits a photon with a wavelenght according to that transition, and we can see that line in the spectrum of that star? But...

Hi there! I'm studying that if r is the quantum number associated with the total angular momentum of a diatomic homonuclear molecule, then only odd or even values are allowed for r. Now, the selection rules for r requires a change of one unity, but if my molecule has only odd values for r...

Homework Statement Write the volume element of d3p as a function of "nu". Assume spherical symmetry in doing this change of variables so write d3p = 4\pip2dp. Homework Equations n(\nu)=\frac{1}{e^{\frac{h \nu}{kT}} -1} \epsilon=\frac{2}{h^3}\int h \nu \cdot n(\nu)d^3p The Attempt...

Homework Statement In manipulating transmission spectrum data from GaAs and InP I'm told to "Look up the refractive indices of GaAs and InP in the region of  = 1.0 micron, and use these to correct your experimental data for reflective losses and plot the corrected transmission T’ in...

I have m(t)=0.2sin(w1*t) + 0.5cos(w2*t) ---> Note: the 1 and 2 besides "w" (omega) is not a coefficient, its a subscript to show that they are different. I found the Fourier transform to be M(F)=0.25[∂(f-f2)+∂(f+f2)] + 0.1j[∂(f+f1)-∂(f-f1)]. My question is, how do I sketch the magnitude...

This is a problem intended to show us that Astronomers are sometimes fooled into thinking that a cosmic source of radiation is thermal, when it is not. Here is the problem: Consider a cosmic source emitting one hundred solar luminosities all within 1 MHz of the single frequency of 22 GHz...

RAMAN spectrum of iron oxide ! Dear every one! I have just got a new raman spectrometer to study the corosion of metals. i tested it on liquids (alcool, benzene, solvant ...) it works very well. i did also experiments on coal and carbon, perfect ! but when i tested on iron oxide .. i got no...

Homework Statement For a downtime analysis the spectrum of motion has to be calculated with the wave spectrum and the RAOs (given) for several frequencies. Given is a wave scatter diagram with the significant wave height (Hs) and the peak period (Tp). How convert the significant wave height...

Homework Statement Much as the title says, I need to construct an example of a linear operator on Hilbert space with empty spectrum. I can very easily construct an example with empty point-spectrum (e.g. the right-shift operator on l_2), but this has very far from empty spectrum. If I...

I have a spectrum analyzer and pulse generator. I decided to see what the spectrum of a sequence of pulses was and found some surprises. The pulses have very fast rise and fall times (5 nanoseconds) with a pulse width of 30 nanoseconds. As a result I obtained the classical (Sinx/x)^2 power...

When white radiation is passed through a sample of hydrogen gas(atoms assumed actually) why are absorption lines observed in Lyman series only? The corresponding photon energy range for visible light(380-780nm) are 1.59-3.27eV which should cause transitions of electrons in the first excited...

where can I get information about the excitation levels (gamma ray spectrum) of a single proton nucleus?

I wanted to know if there was a standard way of finding out the spectrum of a Hamiltionian given a specific H. For example, H = -\Delta - 10|x|^{3} + |x|^{4} or H = -\Delta -(1+|x|)^{-2}. I don't need answers to the above, I just want to know if one can describe the spectrums of...

Hello, We are all familiar with the standard classification of Radio, Microwaves, Infrared, Visible Light, Ultraviolet, X-Rays, and Gamma Rays. But I had some questions about why these parts of the electromagnetic spectrum are the way that they are. I know it is characterized by the wavelength...

I'm looking in a textbook at a discussion of a semiconductor quantum well which is being irradiated and an absorption spectrum produced. Electrons are being promoted across the band gap and holes are being created. There are heavy hole and light hole transitions, and the spectrum shown rises in...

I understand that the sun is made of 91% hydrogen, 8.7% Helium, and 0.3% other stuff. I looked up the atomic spectrum for helium and hydrogen [within the visible portion] and they leave most of the spectrum blank, albeit few lines of colour here and there, yet the white light that reaches us has...

Homework Statement Draw the skeletal structure of the compound with molecular formulaC3H4Cl4 whose proton NMR spectrum contains a down-field triplet and an up-field triplet with relative integration of 2:2. 2. Rationale for Solution Integration ratio of 2:2 means CH2-CH2, after this one carbon...

Hi everyone, I'm having some problems with this topic. how to numerically calculate the energy spectrum for a certain Hamiltonian? eg., in a periodic potential or disordered potential: \widehat{H}=-\frac{\partial^{2}}{\partial x^{2}}+cos(x)+V(x) Thanks for your time and attention.

In my organic lab we recently isolated and crystallized the natural product usnic acid from dried lichen. An IR spectrum of the crystals dissolved in mineral oil was obtained, but it came out looking a bit strange. The thing that's really confusing me is that there is no band that would be...

Can any wavelength of the electromagnetic spectrum cause objects to heat up? If you shined a bright enough flashlight at someone through a vacuum, would they start to feel warmer? What about if you directed radio waves at someone (If they were intense enough)? Could that cause them to heat up...

Homework Statement My teacher posted this solution. It is exactly what I had, except I did not have 4Pi in the numerator. Rather, I had 2 instead of 4, and I didn't have Pi. The solution manual has had mistakes before, so I am wondering if that's what the case is here. Every other step, I had...

When we first realized that the further away a galaxy is the further towards the red side of the spectrum it was, we beleived this to be do to the expansion of the universe? Wouldn't it have been simplier to say that the further away a galaxy was the further the wave function stretched over...

Homework Statement Determine the wavelength (in nm, to one decimal place) of the line in the emission spectrum of the He+ ion produced by a transition from n = 3 to n = 1. Homework Equations I used the Rydberg equation for this, although I'm not sure it is the correct one to use...

I am posting this for an EE engineer friend, need suggestions/link(s) to a USB Spectrum Analyzer. The more compact the better... Thanks in advance... Rhody...

Homework Statement I am trying to understand the allowed eigenvalues for the angular momentum operators J and L. In particular why, mj can take integer and half-integer values whereas ml can take only integer values. Homework Equations I have learned about angular momentum operators as...

Hi... I m unable to find the answer for these questions... Q. What are electromagnetic waves? State its properties. Q. What is electromagnetic spectrum? Describe complete em spectrum from gamma rays to radiowaves in terms of frequency,wavelength,production, atleast 2 properties...

I was reading an article on spread spectrum clock generator here - http://www.maxim-ic.com/app-notes/index.mvp/id/1995 Wouldn't spreading the frequency from the center frequency affect the data transfer? In case of a CPU, the speed would vary too. I understand spread spectrum in...

Hi all I'm unsure about something and so would like to pose the following question. When an electron moves to a lower state it emits energy in the form of a photon. But in order to get excited into this higher state it must first receive a minimum amount of energy. Is the energy received...

Hi everyone, i want to operate spectrum analyzer by pc or laptop. Is there such interface of spectrum analyzer and pc possible? If yes, then how? Tell me the name and contact detail of person who have make such interface..

Hi! I'm trying to understand how do i get the phase spectrum from a Fourier Transform. From this site http://sepwww.stanford.edu/public/docs/sep72/lin4/paper_html/node4.html#lin4_swhfactm this statement "The phase spectrum is usually calculated by taking the arctangent of the ratio...

can anyone explain what is d band and g band in the Raman spectrum of graphene?

Hi, I've got a (confusing) question about string theory. Analyzing the massless modes of the closed string gives me three fields, which correspond to the fact that reps of the group SO(D) (or SO(D-1,1) ) can be breaken apart into three irreps: *A symmetric traceless part *An...

Anyone knows if the CMB map of anisotropies from WMAP is used to implement the angular power spectrum plot(acoustic peaks)? I'm not sure, but I tend to think it is not.