how to calculate the intensity of fluorescence emission?
409827
Try this site. I have no clue, just trying to help.
802629
Let's assume that the energy of the Cl - Cl bond is 328 kJ/mol.\nSo that's how much energyis needed to break it.\n\n328 kJ/mol = 5.49 x 10^ -19 J/molecule\n\nUse E = hf  (E = energy, h = Planck's constant) \nto find the frequency (f) of the light with that much energy.\n\nThen, use the universal wave equation v= f(lambda) where v is the speed of light, and lamba is the wavelength, in metres.\n\nGood luck !
925293
c = lambda x nu\n\nc is the speed of light 3.0 x 10^8 m/s\n\nlambda is the wavelength\n\nnu is the frequency
839143
Here's a calculator, but 1 candela = 1 lumen/steradian where steradians are calculated from the angle of the beam.
899107
Quantitative = amount \nSpectrophotometric = wavelength specific measurement\nAnalysis = determination\n\nCombining these terms gives you "the determination of the amount of material present by the use of specific wavelengths of light".\n\nMany compounds have chromophores, or specific portions of the molecule, that absorb energy of a specific wavelength.  Therefore, using a spectrometer, you can determine that a light source produces a given amount of energy at some predetermined wavelength.  When the analyte of interest is inserted into the light path, some of the energy will be absorbed, which will be proportionate to the amount of material present.  (Increasing the amount of material will absorb more energy, decreasing the amount of material will absorb less energy.)\n\nBy comparing the unknown material to a series of samples prepared in known concentrations, you can determine the concentration (amount) of the unknow sample.  The actual formula for this process is known as the Beer-Lambert Law.
1166133
Multiply both sides by R+r\nI(R+r) = E\nDistribute the I\nIR + Rr = E\nSubtract IR form each side\nRr = E - IR\nDivide both sides by R\nr = (E-IR)/R
546696
Ok, So you know the Time, the Starting mass we'll say Ao, and the Half life.  So by the equation:\nA/Ao = (1/2)^n,\n\nwhere A is the amount remaining, Ao is the starting amount and n is an integer, which needs to be determined.\n\nn = T/(t)\n\nWhere t is the half life and T is the time elapsed.  \n\nSo you first solve for n, and then derive the expression for A.  you should get the equation,\n\nA = ((1/2)^n)*(Ao)\n\nThat'll give you the new mass and from the mass you can use Avogadros number to determine the particles emitted.
835734
-0.070, -0.001, 0.000
994673
I am not sure of the final answer you are looking for.  If you are looking for the number of molecules transferred after a certain time t, the answer is simply n=-DAt(dc/dz).  This of course assumes that dc/dz remains relatively constant.  If not you will need a dc/dz as a function of t.
1185872
I can think of two ways to measure the absorption and reflection coefficient of a material.  The first would only work with a polished surface.  First measure the intensity of a laser beam with a photodetector, then shoot the laser beam at the surface and aim the reflection at a photodetector.  Coefficient of reflection = transmitted intensity/initial intensity  (coefficient of absorption =1-reflection).  The other, harder way, which would work with any material, is to measure the heat gain in the target.\n\nFor this you're gonna want as small a piece of the target material you can get so that the laser still completely hits it.  Now attach a thermistor to the back of the target (again the smaller and thinner the target the better, ideal would be a foil just thick enough to be completely opaque).  Now shoot the laser at the target and measure the temperature as a function of time  It should be linear up until it starts radiating nearly as fast as it absorbs energy, so take points until it starts to level off and drop points after that.  Now find the specific heat of the thermistor-target apparatus by dipping it in water with a thermometer in it, using the initial and final temperature of the water, the volume of the water, and the initial temp of the apparatus, determine the heat it absorbed per degree it's temperature changed (this will actually give you specific heat*mass which is fine).  Now convert your temperature vs. time data to heat vs. time using the specific heat you determined (temp*(specific heat*mass)).  The slope of the line of best fit for this data will give you the rate it absorbed energy in watts.  Divide this by the lasers output in watts and you get the absorption coefficient.
737785
I'll let you do the calculation, but the equation you need is:\n\nE = hc/lambda \n\nwhere h is Planck's constant, c is the speed of light in m/s and lambda is the wavelength of the light (in meters). You can find the rest of the numbers in your text book, I'm sure...
501994
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/posfe.html#c3\n\nThe link above may be of some help. Input the values you want or need.
228649
CO2 + H2O + light = C6H12O6 + O2
727216
use beers law to figure out the concentration and then take that to mole ratio
920352
Did you measure the absorbance of a standard in addition to the unknown sample?\n\nIf so, you could plug the values into (As / Au) = (Cs / Cu)\nWhere\nAs = Absorbance of the Standard\nAu = Absorbance of the Unknown\nCs = Concentration of the Standard\nCu = Concentration of the Unknown?\n\nAlternatively, did you get a value for the molar absorptivity of PNP at the wavelength you used? \nIf so, you could plug it into\n\nA = (epsilon)(b)(c)\n\nWhere\nepsilon is the molar absorptivity,\nb is the length of the path through which the light passed,\nc is the concentration of the chromogenic substance.\n\nAnd you could rearrange that to solve for c.\n\nHope it helps
291779
You can view fluorescence under different wavelengths, like Blue and Green light. Fluorescence always requires the excitation of an electron by light soource, the energy that is released caused the fluorescent signal. Some organisms autofluoresce like certain bacteria, plants and algae, but you have to view them under an excitation light.
1103364
each magnitude corresponds to a ratio of 10^(-.2), so you want to multiply the (-.2) by (1.9) and look at 10 to that power. This gives the  fraction of photons that make the trip.\n\nHomework and repeat question.