03/7/2018

Standard Operating Procedure For IPCE

Preparation

1) On the computer, log on to “choi”: password is “kschoi”2) Bring over blue potentiostat from photostation 2 or 3. (You will need the potentiostat cable, but

the power and ethernet cable are already at the IPCE setup.)a. Attach the potentiostat cables to the appropriate cables in the back of the Faraday cage

(for best electrical connection, clip wires as seen in the picture below)b. Plug the black cable into the green plug in the back of the potentiostat (this grounds the

Faraday cage which is important for proper function)

2) Turn on the Xe lamp (and light for 30 min), luxmeter, monochromator, and potentiostat.

a. Xe lamp power supplyb. Xe lamp housingc. Filter holder box

i. Place the 0.2 neutral density (ND) filter first to absorb the harshest light before the AM 1.5 filter (Filters are held by spring loaded brackets. Remove with care by pressing up on the button on bottom of filter holder compartment).

a

b ced

f

g

ii. The next filter is order sorting filter. Use the round clear order sorting filter (Newport #59450, UV-C and B blocking filter, 325-2700 nm transmittance). Remember to replace top of filter holder when filters are in place.

d. Potentiostate. Monochromatorf. Luxmeter

i. Rest on the faraday cage. Plug into power strip and into existing data cable from back of IPCE computer.

ii. Instead of using a thermopile detector (SUD 623), attach HNK 15 tube to SED 033 Si photodiode detector. Then, attach it to back of luxmeter the same way as the thermopile detector was attached.

g. Faraday cage

Calibrating light source to proper intensity

1) Change calibration factor on luxmeter to #3.a. Press factor shift once (red light should change) and then press factor select until the

display reads “3”. b. Then press factor shift to begin reading data again (red light shoud change back to

“data”).

2) Open Monochromator Control program (Monochromator must be turned on first)a. Set to 470 nm and click Goto (blue light). b. Then click “shutter” and open. c. Use clear round order sorting filter (Newport #59450).

HNK 15

SED 033

3) Place the detector on the stir plate with the quartz slide pressed directly between the fiber optic cable and the detector.

a. Adjust the positioning so the center of the detector is directly illuminated by the blue light from the end of the fiber optic cable and secure the detector with some tape.

b. The small mirror helps with horizontal alignment and stacking 5 CD cases is usually good for the vertical alignment, see picture below.

c. Slightly adjust the horizontal position to maximize the intensity reading. d. Close the door to the shielded box as much as possible using the upper screws (the

detector cord should come out from right corner and prevents fully closing the box). e. It is good to tape the cord to the bottom right.

4) Close the shutter in the monochromator control program and zero the detector. (wait for the red dot to go back to “DC” before proceeding)

5) Open the shutter and a. Adjust the intensity using the knob on the rotating black barrel attached to the

monochromator. (see below)b. Intensity should be adjusted to read 2.60 x 102*. Double check by closing the shutter,

zeroing the intensity and reopening the shutter.

* The calibration factor is calculated for μW/cm2, assumes the area as 0.196 cm2 and 470 nm illumination. Raw reading of luxmeter is approximately 3.12 x 10-8 A (Value reading at the factor #2). This can be divided by the calibration factor provided in a table from the detector document (6.116 x 10-4 A/W @ 470 nm), which gives about 5.10 x 10-5 W and when divided by 0.196 cm2 and multiplied by 106 μW/W gives 2.60 x 102 μW/cm2.

Obtaining a background light intensity plot

***Close the Monochromator Control program. The IPCE Background program won’t connect with the Monochromator Control program still controlling the monochromator.***

1) Switch detector to “factor #2” (raw intensity reading in A), a. Make sure the red light is back to “data” afterward.

2) Open IPCE Background program a. Make sure the data cable is connected between luxmeter and IPCE computer.

3) Go to “Oriel Cornerstone” tab under “Acquisition Config” tab a. Click “connect” (if an error message pops up ensure the luxmeter is on and connected

and that the monochromator controller is closed)b. Input scan range for the monochromator in nm from high to low (1st value is the

starting, 2nd is the pause point for switching filters if needed, and 3rd value is the ending). c. For wavelengths >600 nm use yellow sorting filter (Newport #59502); for wavelengths

<600 nm use clear sorting filter (Newport #59450)

Do not touch

Adjust

4) Move to “Scan” tab.a. Check that the illumination area is set to 0.196 cm2 b. Click “Scan Intensity”c. When prompted, change the order sorting filters then click “OK”.

5) “Save Data” to *.csv file. (This data is going to be used in IPCE calculation).6) Close IPCE Background program7) For Luxmeter

a. Set the Factor select back to “1” for thermopile detector.b. Change detector back to the thermopile detector.c. Turn off and put back near photostations 1 and 2.

Collecting IPCE photocurrent measurement

WE clip

CE plug

WE

CE

RE

RE plug

RECE

WE

1) Set up a typical 3 electrode experiment and use pen electrodes for WE and CEa. Attach the WE pen electrode to the red alligator clip, b. Plug the CE pen electrode into the blue plug, c. The RE plugs directly into the white plug

2) Open “EC lab” a. Set up a chronoamperometry experiment to collect I vs. t at a constant potential. b. Set data collect to be either every 0.25 to 0.5 seconds. The more frequent the data

collection, the better the data will be, but it will be more difficult to process the data. Do not collect by change in current.

c. Choose the potential you wish to apply and set the stop time to a high value like 100 h. (its better to stop the scan when you want vs. it stopping before its actually done)

3) reopen “monochromator controller” and setup scan parameters

a. Set start wavelength and end wavelengthb. Make sure the scan direction is toggled to the correct (UV or IR) directionc. Set the pause time. (10s is a safe starting point, but check to see what works best for

your particular material)d. Set the current wavelength to the start wavelength and close the shutter. e. If you are starting above 600nm, scan from your starting wavelength to 600 nm. Once

this is complete, you will change the ordering filter and set up a new scan from 600 nm to 300 nm. (there is no pause for changing ordering filters)

4) Start the chronoamperometry experimenta. Wait for the dark current to stabilizeb. At an exact minute value (ex: 120 seconds), start the IPCE scan by clicking “Go Scan” (by

starting the scan on an exact minute it is easier to process the data later)c. Wait until the scan is done then stop the scan

5) **If starting above 600 nm**a. Scan from start wave length to 600 nm.b. Do not stop the chronoamperometry experimentc. Change ordering filtersd. Change the scan parameters to 600 nm start wavelength and the desired end

wavelength.e. Wait until another exact minute value and start the IPCE scan again by clicking “Go

Scan”f. Your Ec-Lab data will now have a period of dark current in between scans which will

help to identify when the second scan was started. (this will however give you data for 600 nm twice both at the end of the first scan and the beginning of the second)

IPCE Calculation Using Obtained Data

Take the data from the IPCE measurement at each wavelength in μA/cm2, the data from the background light intensity scan (μW/cm2), and plug them into the below IPCE equation.

IPCE=1240×i photo (μA /cm2 )λnm× j photons (μW /cm2 )

×100 (%)

We have an excel document to calculate the IPCE and APCE.