Spectrum Definition and 725 Threads

Homework Statement This question is about microwave (rotational) spectroscopy. Which of the following molecules have a microwave spectrum? H2, N2, NO, N2O, CH4, CO2, OCS, H2O, Ethene, Benzene. The Attempt at a Solution According to my textbook, it appears that all molecules have a...

In the standard inflationary scenario, the power spectrum is evaluated at the cosmological time when one assumes an equation of state $ P= \omega \rho$ , that is, one is assuming a particular radiation or matter dominated universe. Why does it has to be in these cosmological epochs? does it...

Hi all, I'm having some trouble understanding the consequences of directly changing the frequencies in the spectrum of an audio signal. Let me give you an example: Let's say I have some audio signal, which I convert to a spectrum (in LabView, using a direct cosine transform (to avoid...

Do all types of light in the radioactive spectrum emit heat? If so, why is infrared the only one associated with heat?

can anyone tell me the relation between phase spectrum and frequency spectrum in signal processing. thanks a lot in advance

I've never really taken any chemistry before so I'm currently taking a class and the more I learn about it, the more interesting it becomes. :smile: However, I do have a few questions (you might find simple) that are kind of bugging me as we begin to progress through the chapters... 1. When...

Why is the frequency spectrum of a sampled signal replicated? We have a Low pass filtered signal sampled well above nyquist rate. I can't understand why the spectrum is replicated.

Homework Statement Radiation with the wavelength 5.0x 10^-6 Meters belongs to what region of the spectrum ? Homework Equations None really. The Attempt at a Solution I don't really know how to read the spectrum too well, but it looks like Infared, am I right?

Hi guys, I'm not rlly sure why certain electromagnetic waves (in the electromagnetic spectrum) travel slower in other mediums apart from in a vacuum (all the waves travel at the same speed)? I tried to search this and found out tht the wavelength of waves decreases when in a denser medium like...

The notion of spectrum in algebraic geometry seem to be a bit abstract to me. Is it a set of points? Is it the analogue of spectrum in Fourier transform?

we can see very hot fire and we can see cold fire. when fire is very hot it turns blue. now someone told me the spectrum of light from hot sun and cold planet are the same when checking a ray, i ask, how can it be? a ray of light coming from a very hot sun should be in a spectrum dominant by the...

Hi, Let E(r,t) = E(r)exp(-ikz)exp(iwt) be a plane wave in time domain, propagating along Z direction. I wonder how to find the spectral representation of it (i.e. E(r,w))?? I know, for a finite intensity field (i.e. |E(r,t)|^2 < infinity), we can give...

Hi, I'm new to the subject and I've been trying to catch up quickly, but something that's been bothering me is why exactly do Microwaves heat waters, fats, etc., even though things with a similar frequency and wavelength(Radio waves, Infared) do not, or at least as quickly?

Hi all, I have not seen a separate section for photonics, so I'll post my question here : Does anyone have measurement data of the absorption spectrum of (liquid) water in the wavelength range of 180 - 250 nm ? Thanks :smile:

I keep seeing the hydrogen emission spectrum from the Balman series (when an electron falls to n=2). It's all over my textbook. Why don't I ever see the Lyman series or any other series? Is it really rare for hydrogen electrons to fall to energy levels other than n=2?

1. Homework Statement How many peaks will there be in the NMR spectrum of Malic Acid, HOOC CH2 CH(OH) COOH, WITHOUT D2O as the solvent (i.e. Hydrogens in Hydroxyl groups WILL have corresponding peaks)? 3. The Attempt at a Solution I thought the two -COOH groups will be identical...

Homework Statement How many peaks will there be in the NMR spectrum of Malic Acid, HOOC CH2 CH(OH) COOH, WITHOUT D2O as the solvent (i.e. Hydrogens in Hydroxyl groups WILL have corresponding peaks)? The Attempt at a Solution I thought the two -COOH groups will be identical Hydrogen...

Homework Statement I have conducted an experiment which attempts to calculate the range of the visible light spectrum. Basically white light was shined through a diffraction grating (300 lines/mm) and diffraction theory is applied to calculate the wavelength. So, here are the variables...

Hello there, my physics friends. I was hoping ye could answer a wee question I have on the phonon spectrum. Mainly,what is it? I know one of the mediations is sound but that's about it. If possible could you put it in terms similar to that of the electromagnetic spectrum. Thanks in...

Homework Statement Part a) The emission spectrum for Sodium lamp contains a reasonably bright red line in its spectrum. What is its origin? Part b) The possible transitions between electron energy levels for Sodium were analysed. There were no transitions between the s series (s subshell)...

I was doing an undergrad experiment on the sodium emission spectrum and I have a few queries. Of course, I was asked to analyse the famous yellow doublet which I'm on top of. I was also asked the analyse the diffuse series which was fine too. What I did notice however, was a strong red line...

let us suppose we have two boxes labelled by A and B i can not open none of them (the boxes) but i can use an spectrometer to measure the absortion and emission spectrum i chek that the eigenvalues of both systems are equal , then my question is A and B boxes contain the same QM system...

Homework Statement In Gasiorowicz's textbook, he provided the schemetic expession of the wave function(95page) ; psi(x) = Sigma[C_n X U_n(x)] + Integral[dE C(E) X u_E(x)] ("X" means multiplication symbol) In this equation, I think that 1st term(sigma) is the case of the discrete spectrum and...

Hi I'm trying to get my head around this plot of the cosmic microwave background radiation. http://www.astro.ucla.edu/~wright/CMB-LCDM-w-WMAP.gif I've been searching all around to find out what exactly a angular power spectrum is. I know what an ordinary power spectrum is. I'm a second...

A detailed picture of the Hydrogen red line shows a lot of detail: The difference in the 2 largest peaks is the fine structure, the lamb shift is clearly noted, but what are the other 2 bumps just below the lamb shift in the upper chart. I was thinking hyperfine, but I don't think that...

I need blibiography of analysis of the spectrum I read in B. Green pp 113, but I no understand.

Okay, I don't know if this is the proper place for this or not, so if it needs moved, move it. But here's my question. If the EM spectrum has no upper limit. Is it possible to have a waveform who's wavelength is twice the size of the known universe? This would put the observable universe within...

what the energy spectrum to second order in the field strength for a spherical shell?

Homework Statement Prepare a table of spectral lines by color, with correct wavelengths, and corresponding energies for every line spectrum you observed. Pick one line spectrum and explain the order of color from least to most energeticHomework Equations I'm not quite sure what to do here. I...

I'm doing a project about astronomy. I've never done one, I just jumped from quantum physics to here, so I don't think I know anything =.=. To start, I think I need some stars spectrum, but since stars are not as bright as the sun, I don't really know how to have them. Could someone give me some...

Hi, I've been measuring the flux of cosmic ray muons as a function of zenith angles. I have calculated the flux but do not know an equation to calculate the energy flux associated with it. My scintillator stops muons that are and below 150MeV if that's any help

Uhm...I'm doing some experiment with some unknown gas tubes. I have a spectrum when I use the grating. Can I, by some ways, use the quantum numbers to identify what the gas inside is...? I've heard of one method, but I could not find the name. Thank you in advance.

*This isn't actually coursework but i was under the assumption that questions go to this forum* Homework Statement Hi, for while I've been under the impression that spectral lines of all the elements can be calculated. I did some research and found that there is a simple equation (Rydberg...

The spectrum tubes work by runnig an electric current through a sealed tube containing gas. What common use of this method can you think of?

Hi, I'm trying to think up a way to shift IR rays into visible light spectrum so that the human eye can effectively see the IR image. Is it possible to do such a feat with something as simple as goggles made from a special material (e.g. anti-stokes pigments)?? If not possible with such...

Homework Statement Let the baseband signal be s(t)=cos(2πfst+π3), where fs=5kHz. Radio carrier is c(t)=sin(2πfct), where fc=100MHz. Using the amplitude modulation of g(t)=(1+s(t))c(t), what is the frequency spectrum of the modulated signal g(t)? What are the amplitude and phase shift of...

Homework Statement In the rotation spectrum of 12C16O the line arising from the transition l = 4 -> 3 is at 461.04077GHz, while that arising from l = 36 -> 35 is at 4115.6055GHz. Show from these data that in a non-rotating CO molecule the intra-nuclear distance is s ~ 0.113 nm, and that the...

Homework Statement What region of the electromagnetic spectrum contains wavelengths the size of an atom? (10^-10 meters) What frequency does this wavelength correspond to? Homework Equations velocity=wavelength(frequency) The Attempt at a Solution 3x10^8/1x10^-10=f i think i...

Hi Is there any other effect than the Zeeman effect that can broaden a spectral line in a magnetic field? /Johan

calculating the stable orbitals for multielectron atoms is so complex that AFAIK it can't be done accurately. so how does the electron in the ground state 'know' that if it jumps to a certain energy level that it will be stable? (which it apparently does know since it 'knows' exactly what...

Lots of works about the high-order harmonic generation in the intense laser-atom physics obtain the harmonic spectrum by Fourier transformation of the dipole moment d(t) (=\int\varphi\varphi^{*}z): p(\omega)=|\frac{1}{tf-ti}\int d(t)exp(-i\omega)dt|^{2} Here, I want to use the Monte-Carlo...

Hi, I have an image of a graphic describing the spectrum of a supernova Ia, the problem is that I don't really know how to read it. I'd like to know if there's any importance in this image that can drive us to think about dark energy (or accelerated expansion). The explanation of the graph...

Homework Statement Find the energy spectrum of a system whose Hamiltonian is H=Ho+H'=[-(planks const)^2/2m][d^2/dx^2]+.5m(omega)^2x^2+ax^3+bx^4 I gues my big question to begin is what exactly makes up the energy spectrum. I know the equation to the first and second order perturbations...

This is more of a data analysis question than a mathematics question so feel free to move it to wherever you think it is most likely to be answered. I have some time series data that looks (just by eye) like it should have several peaks in its power spectrum. However, when I compute the power...

Hi! The question is Suppose we are irradiating a sample of a low pressure gas and some of the radiation is absorbed. Some books say we will obtain a discontinuous spectrum! But if we are irradiating a sample of a low pressure gas we will have absorption and emission at the same time and the...

Homework Statement What is the minimum number of lines per centimeter that a grating must have if there is to be no second-order spectrum for any visible wavelength? (Let visible region extend from 400 nm to 570 nm.) Hint: Draw a diagram showing the relative positions of the rays corresponding...

I am interested in finding and understanding the relationship between the hydrogen spectrum (which of the lines are more intense) and the pressure that the hydrogen gas is under. Does hi-pressure gas mean lots of ultraviolet or hardly any? Is there a chart somewhere? TIA

So I have a power spectrum of a given function, which is supposed to be a superposition of four sinusoidal terms with frequencies that range from 1xomega to 4xomega. My spectrum looks something like this: http://upload.wikimedia.org/wikipedia/commons/4/4f/Triangle-td_and_fd.png What exactly...

URGENT spectrum lines Homework Statement A diffraction grating (with 10,000 lines per cm) is held 2 meters from a Hydrogen lamp (lamp which emits Hydrogen’s spectrum). As you look through the diffraction grating a blue line is observed to lie 1.11 meters on either side of the lamp. 1) What...

I don't mean to violate any rules or conventions; these are questions pertaining to labs I'm doing as part of an undergrad degree. It's not homework, as such, so I've not put it in one of those forums But my apologies if this is incorrect. Anyhow; the experiment that bothers me is a...