Absorption Definition and 534 Threads

In school, I have been told that black appears how it is because it absorbs all frequencies of visible light and reflects no frequencies of visible light. Following that logic, if one were to shine a flashlight in a dark room where the walls, ceiling and floor were all black, one would not see...

Hello guys, i have saturated spectrum of Rb. My goal is to identify which lines i see. http://imagizer.imageshack.us/a/img835/8787/xvwr.png So from http://www.opticsinfobase.org/oe/fulltext.cfm?uri=oe-15-10-6293 I have identified that there are to 2 Isotopes: Rb85 and Rb85, further from...

I'm trying to understand the form of the absorption spectrum of a T=0K intrinsic semiconductor. The valence band/conduction band energy diagram looks like; http://postimg.org/image/wyzvo9lsr/ As E = \frac{\hbar^2 k^2}{2m^*} where m^* denotes the effective mass. The image doesn't...

Something I've yet to understand: If a molecule has a dipole moment about a given access than absorption of a photon can readily occur. However, if it is possible to preferentially orient molecules by applying an electric field, would the rate of absorption be greatly increased or decreased? It...

I have been toying with an idea that may break the second law of thermodynamics for a while now, but it is basically this; An endothermic reaction is used to convert heat energy into chemical energy, and then the products of that reaction are used as the reactants in an electrochemical reaction...

Why cold gas is used for producing an absorption line spectrum

Hi everyone--first post, thanks for any guidance if I've posted in the wrong place. I've got a simple idea and I'm curious if it's worthwhile doing. How effective would putting a dark surface (perhaps black tiles, or black corrugated plastic) on the bottom of the pool, to warm the water by...

I cannot wrap my head around this stuff. Sorry if long post. I understand that emission lines come from a higher energy state dropping to a lower state. This happens at discrete energy levels, which should correspond to discrete frequencies. And the same atom should be able to absorb photons...

I understand that the purpose of a damper system is to stop the spring from bouncing during rebound. But,technically speaking,I do not understand the matter of energy absorption in the damper during rebound. 1.The damper is absorbing energy during compression along the bump and dissipating...

Hi, I have just registered to ask something that I can't find the answer anywhere. As you know, microwaves are absorbed by water molecules because of its shape and angles etc. I wonder which wavelength can be absorbed by nitrogen molecules in the air or at least need to learn a method to...

On an intuitive level, Why do stars show absorption lines? For example, the 121.6nm photon is produced when an electron falls into the lowest level of a hydrogen atom. A 121.6nm photon is absorbed by a hydrogen atom being kicked into an excited state, where it will eventually emit a 121.6nm...

Hello all, I am looking for easy to obtain materials, preferably in powder form, with good absorbance at 808nm, 365 nm and 404 nm each (either one material for each wavelength or one for all three).However I can't seem to find absorbance charts. Does anyone have any idea either on which...

Three bodies 1,2,3 are in closed region. Region is at temperature ##T##. ##e_{\lambda,T}## - spectral emission power ##a_{\lambda,T}## - spectral absorption power In experiment...

Hello people I need your help. I am kind new to refrigeration and I want to design one. I have a waste exhaust heat from the Exhaust of the tunnel oven that I have designed. Now I want to use that waste heat as the heat source for the Absorption refrigerator. Q1: what's the best solution I...

What are the properties that make materials reflect or absorb a certain EM wave or just allow it to pass through ( transparency ) ??

First, let me see if my facts are straight. White coloured objects reflect more light of ALL frequencies than black coloured objects, including infrared, etc. Hence a white coloured object is cooler than a black coloured object. If visible light was the only factor, a blue room would be cooler...

I have to write some training on the following and I really have no idea. Is this correct? Any help is greatly appreciated;) Inelastic scattering In inelastic scattering, a neutron collides with and is temporarily absorbed by the nucleus of the target particle. This excites the nucleus...

Perturbation theory predicts rates of transitions between eigenstates of the unperturbed Hamiltonian, which in the independent electron model for a crystal are nonlocal Bloch wave functions or linear combinations of them that extend throughout the crystal. However, photon absorption is...

Hi everyone, I just wanted to double check on a fundamental concept of quantum physics. Let us consider a monochromatic beam of photons,incident on a material(of a finite thickness,say 15 cm.) which reflects, transmits, and also absorb photons. Now, in QED by RP Feynman it is stated...

This post specifically queries the absorption, by matter, of (thermal) radiation which has been emitted from a source of a cooler temperature than the receiving matter. As I understand it, when matter 'receives' radiation, that radiation is either a) absorbed, b) reflected (or absorbed and...

i was reading papers and also doing my own simulations for a reflectivity experiment. i noticed though that reflectivity peak say at 3eV will correspond to a absorption peak (in the complex dielectric) at about 3eV too. I'm just confused here because we all know that R + T +A = 1. But yet...

Homework Statement An EM wave is incident normally on a surface which absorbs all the electric field. Using maxwell equations, determine B-field on the other side. Homework Equations The Attempt at a Solution If all the E-field is absorbed, won't ET and Er = 0? Then none of...

The definition of the Gaunt factor. Hello. I'm wondering about the Gaunt factor. I'm currently interesting in the spectroscopy in which the Gaunt factor is the correction factor to the classical cross section associated to the photon with electron thus the corrected formula is the identical...

Homework Statement In uranium (Z=92) the K absorption edge is 0.107 Å and the Kα line is 0.126 Å. Determine the wavelength of the L absorption edge. Homework Equations K-edge: EK= (Z-1)2*13.6 L-edge: EL= (Z-σL)2*13.6*1/4 what is σ and how was calculated. Characteristic X-rays: Ex = h*ν=...

Hi everyone, I have a problem a bit tricky to solve which deals with Infrared absorbers. In my setup experiment, some IR radiations are emitted, let's say black body radiations at 300K, so IR wavelengths centered on 10,6µm. I want to absorb them (entirely) by a surface (at about 77K) made...

Hey, so I am trying to figure out the optical path length change of an optical fiber due to absorption. I'll post what I have so far and let me know if I have done anything wrong or if you have suggestions. so the optical path length is L' = nL (L' is optical path length, n is refractive...

Does reducing acceleration mean reducing force acting upon the object. And does this mean absorbing energy from the object? If so where is the energy absorbed in case of crashes where air bags inflate to reduce force?

Anyone know an equation for comparing water absorption by plotted plants vs. evaporation of the water collecting in the pot's water collector? That is, if I water a plant and much of the water leaks through to the collection area how much of that leaked water will evaporate vs. be absorbed by...

When analyzing the absorption pattern for different compounds when radiated by IR radiation, we see the wavelengths of the IR lights that is absorbed. These wavelengths correspond to the frequency at which the bonds in the molecule vibrate. My question is why a compound, for example an alcohol...

Hello, I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index? p.s. I am trying to...

Hi, I'm confused about reflection and absorption in materials. Is glossiness of an object determined by roughness of its surface rather than its inability to absorb visible light? If there are dark-colored objects where one has a matte finish and the other has a glossy finish, does this mean...

Homework Statement For a lightly damped harmonic oscillator and driving frequencies close to the natural frequency \omega \approx \omega_{0}, show that the power absorbed is approximately proportional to \frac{\gamma^{2}/4}{\left(\omega_{0}-\omega\right)^{2}+\gamma^{2}/4} where \gamma is...

According to wikipedia, absorption is an axiom for a boolean algebra. This seems incorrect to me, since I believe absorption can be proved from the other axioms (distributivity, associativity, commutativity, complement, identity). Thoughts? ## AB' + A = AB' + A*1 = A(B'+1) = A(1) = A ## BiP

Sorry if I am posting in the wrong place. I'm really interested in the Fourier series, but I'm not an expert on it yet. I am very well aware yoy can do it with sound waves, but can you manipulate any other waves? What about light waves? And for absorption, how can you measure the...

Homework Statement Radiation of intensity I is normally incident on an object that absorbs a fraction frac of it and reflects the rest back along the original path. What is the radiation pressure on the object? Homework Equations Radiation pressure Pr (force/unit area) Pra = I/c...

Hi we know the relation between wavelength, frequency and energy : The greater the energy, the larger the frequency and the shorter (smaller) the wavelength -> E=h\upsilon On the other side, SAR is common property that measures absorbed energy. Now if we calculating SAR for human brain...

Hi there, I've been studying mechanisms by which high-energy radioactive decay products (beta particles, x-rays, gamma rays) are attenuated as they pass through matter. From my readings in introductory and intermediate level textbooks, the general mechanisms by which these particles and rays...

Here is the question: I have posted a link there to this topic so the OP can see my work.

does anyone know anything about coeliac disease and malabsorption syndrome/disease? it can really affect life. I've been seeing specialist doctors including GI specialists for years, one cure for coeliac is a no wheat/gluten diet

hello everyone i am a master student and right now i am preparing for my thesis which is about the ultrasonic absorption for binary mixtures using the dynamic scaling theory that theory has been set by Ferrell and Bhattacharjee if anyone have information about this subject or papers i can...

if objects absorb certain wavelengths and reflect some * which give us its colour* how does this actually happen ? if a certain substance absorbs red colour because it equals the amount of energy * quanta * needed to excite its electron to the next energy level , then shouldn't the electron...

I am looking for an exact value of absorption coefficient of aluminium for microwaves, but I can not find it in the internet. Anyone knows where I can find it?

hi all, i learned that only certain orbits were allowed in the atom and that if the electrons occupied any of the orbits in between, that they would no longer be in a resonance orbit (i was taught that the allowed orbits were the electron probability wave in resonance and therefore no EM...

Does anyone know of a lasing medium (perferably something that can be doped into an optical fiber, but a liquid or gas would work if not) that has a strong absorption at 589.0nm and 589.6nm? Rationale: I'm trying to build a relatively cheap high powered (~300W-400W CW) LASER for DMLS, but...

As far as I know, free electron-hole or excitons can be created by absorbing a photon of relevant energy. So dissociation of excitons shouldn't make any effects on absorption because dissociation happens after the absorption. Nevertheless I saw in some texts that in the limit of the temperatures...

Homework Statement There is a brownian particle in 3D space and absorbing sphere with radius a. At moment t = 0 the particle was situated at distance l from the sphere. Caluclate the probability of absorbing the particle by the sphere. Homework Equations n is probability densithy for the...

Hello, am working with luminescence spectra, including excitation and emission spectra. When you makes an initial characterization of a sample should be done first? an absorption spectrum? At what wavelength excitation should be performed to see the desired effect? Particularly when...

Homework Statement The following photon wavelengths are observed in absorption at room temperature from an ionized atomic gas with a single electron orbiting the nucleus: λ= 13:5 nm, 11:4 nm, 10:8 nm. Use this data to determine the effective Rydberg constant and the nuclear charge...

Hello Can anyone tell me how the absorption of a polystyrene nanoparticles scales as a function of its diameter. The particle is spherical and it is placed in vacuum. A reference to a paper I can read would be nice. At this point I only want to know how the absorption scales not...

After performing this experiment, we will get different peaks on the computer screen, where on x-axis lies thickness of the absorber and on the y-axis the nb of channels. What do these represent exactly? Why do we have a high peak and a medium sized one? What are the significances of each...