Question

Consider the following instrument configuration: A multiwavelength, collimated Light Emitting Diode (LED) with primary emission at 500 nm (50W), 545 nm (25 W) and 600 nm (100 W) is used as a light source. The LED is focused onto bandpass filter with the transmission spectrum shown in Figure 2. The transmitted light is then directed via a series of mirrors onto a standard 1 cm cuvette similar to the configuration shown in Figure 1. Relevant pieces of info are given below.

Answer 1

a. You must choose the material from which to construct the sample cell. If the sample cell is a 1 cm square cuvette with 0.5 mm thick walls, which material would be a better choice for construction of the sample cell from 5 types of Schott glasses listed in the table below? Justify your answer.
b. What is the intensity at point C if two Ag mirrors are used (see reflectance curve below)? Note: values for normal incidence and 45o incidence are the same for this mirror
c. For an absorbance measurement, at what point (a through d) should I0 be measured? Why?
d. If the sample cell contains a non-absorbing species, what is the intensity of light measured at point D if a 1.0 cm F2 sample cell and Ag mirrors are used in the system?
e. If the F2 sample cell contains a solution of molecule X at a concentration of 10.0 M ( = 50,000 M-1 cm-1) what is the intensity of light measured at point D?

Answer 2

Can you post larger versions of the tables? they're all blurry

Answer 3

yeah sure

Answer 4

@Nnesha

Answer 5

Looks fun...this due tomorrow? ;p

Answer 6

nope Tuesday, but got to get it done.

Answer 7

*UPDATE*
I've already got a. now I need help understanding b

Answer 8

@DanJS

Answer 9

b. What is the intensity at point C if two Ag mirrors are used (see reflectance curve below)? Note: values for normal incidence and 45o incidence are the same for this mirror.
I don't know how to do this even a little bit. its not even in my book

Answer 10

@zepdrix please help me?

Answer 11

@mathmale

Answer 12

@JoannaBlackwelder help?

Answer 13

i tagged u

Answer 14

for b) you need the wavelength of light used,

say its 450 nm, after each reflection only 95% of the initial intensity is present

Answer 15

the 95% came from the graph you posted btw.

Answer 16

for c) the initial intensity (\(I_o\)) should be set at the same point where you are making the absorbance measurements. Usually the beam is split, at this point