Thermo Electron Thermo Spectra-Tech Collector II User manual

COLLECTOR™ II
User's Manual
P/N 0030-0XX
P/N 700-0042
Version 3.9
A Thermo Electron business

Table of Contents
General Information
The Manual .............................................................................................................3
Packing and Unpacking...........................................................................................3
Technical Support Center........................................................................................3
Copyrights & Trademarks........................................................................................3
Contact Thermo Spectra-Tech................................................................................3
Introduction to Diffuse Reflectance Spectroscopy...................................................4
COLLECTOR II Product Description.......................................................................4
BLOCKER Description............................................................................................6
Diffuse Reflectance Sampling Technique ...............................................................7
Installation & Alignment
Sample Compartment Baseplate Removal.............................................................9
COLLECTOR II Installation...................................................................................10
Purge Cover/Purge Insert Removal ......................................................................13
Mirror Alignment....................................................................................................14
Mirror Fine Adjustment..........................................................................................16
Purge Cover/Purge Insert Reinstallation...............................................................18
Operation
Using the COLLECTOR II ....................................................................................19
Sample Preparation (Powders).............................................................................21
Sample Preparation (Intractable Samples) ...........................................................24
Factors that Affect Diffuse Reflectance Spectra....................................................25
Appendix A
Mounting Methods.................................................................................................31

3
Collector II
General Information
The Manual
This manual is designed as a tutorial to guide you through the installation of Collector II and
through a typicalanalysis. If you have any questions, please contact a Thermo Spectra-Tech
Technical Representative.
Packing & Unpacking
The Collector II is shipped in a protective foam filled cardboard box. Upon arrival please
check the box to ensure that all pieces have been received and that no pieces are damaged.
Save the box for storage and shipment of the kits.
Technical Support Center
Technical materials describing the use and theory of attenuated total reflectance, diffuse
reflectance and specular reflectance are available from Thermo Spectra-Tech. Additionally,
a team of scientists is available at Thermo Spectra-Tech to answer any of your questions. If
you encounter any problems or difficulties, or desire additional information please contact the
Technical Support Center at 800-THE-FTIR.
Copyrights & Trademarks
This User’s Manual is copyrighted to Thermo Spectra-Tech, and should not be photocopied,
reproduced, or transferred without the express written consent of Thermo Spectra-Tech.
Collector II, Blocker are trademarks of Thermo Spectra-Tech.
All other trademarks or registered trademarks mentioned herein are the property of their
respective owners.
Contact Thermo Spectra-Tech
230 Long Hill Cross Road
PO Box 869
Shelton, Connecticut 06484-0869
Phone: [phone], or 800-THE FTIR
Fax: [phone]
www.thermospectra-tech.com
[email protected]

4Thermo Spectra-Tech
Banner
Introduction to Diffuse Reflectance Infrared
Fourier Transform Spectroscopy (DRIFTS)
Diffuse reflectance spectroscopy is a powerful technique for infrared analysis of fine particles
and powders in concentrations that range from undiluted to parts per thousand (0.1%).
Analyses are fast and easy because little or no sample preparation is required. Powder
samples can be measured “as is” or mixed with a diffusely scattering matrix such as
potassium bromide (KBr). Solids can be ground and deposited on a particle matrix then
measured as a powder.
The Si-Carb™ Sampler, a special tool can be used to analyze large, intractable solids by
scratching the sample surface with an abrasive paper and then measuring the particles
adhering to the paper.
The high throughput and signal-to-noise ratios of FT-IR spectrometers, in combination with
on-axis diffuse reflectance accessories, have made diffuse reflectance a powerful infrared
sampling technique. Currently, DRIFTS (Diffuse Reflectance Infrared Fourier Transform
Spectroscopy) offers a number of advantages as a sampling technique, including:
• Minimal or no sample preparation.
• Very high sensitivity (down to low ppm levels).
• Ability to analyze most non-reflective materials, including highly opaque or
weakly absorbing materials.
• Ability to analyze irregular surfaces or coatings, such as polymer coatings.
• Ability to analyze very large, intractable samples.
For a complete description of the theory of Diffuse Reflectance please refer to
Spectra-Tech's FT-IR Technical Note #2: Introduction to Diffuse Reflectance Infrared Fourier
Transform Spectroscopy.

5
Collector II
Banner
COLLECTOR II Product Description
The Spectra-Tech Diffuse Reflectance (DRIFT) Accessory, “The COLLECTOR II” is
designed for use in FT-IR spectrometers. The design employs 4 flat and 2 aspherical
reflectors, plus an alignment mirror. The aspherics are off-axis ellipsoids which focus and
collect infrared energy with a 6X condensation of the beam. A typical FT-IR beam has from
a 3mm to 18mm spot size at the focus, so the spot size with the DRIFT accessory will be
between 0.5 and 3.0mm. The collection angle is a full pi steridians, collecting 50% of the
available diffuse energy. The Spectra-Tech COLLECTOR II has been designed for high
energy throughput and ease of use. Access to the sample is from the top, by sliding the
ellipsoids out of the way. In addition, a mechanism is provided to slide the sample cup
forward to remove it without sliding open the ellipsoids for additional convenience. This can
be useful for repetitive sampling situations. The sample cup is removable for filling, and the
sample height is fully adjustable. Figure 1 is an optical layout of the COLLECTOR II,
showing the beam path through the accessory.
In order to deal with the “specular component,” which can cause spectral distortions
especially in neat, inorganic samples, a BLOCKER device is provided. This device is
described fully on page 5.
Figure 1 Optical Layout of the
COLLECTOR II
CAUTION: Please note that all mirrors are
uncoated (bare) aluminum. Care must be
taken to avoid damaging or smudging these
reflective surfaces, as they are relatively soft
and difficult to clean without scratching.

6Thermo Spectra-Tech
General Information
BLOCKER Description
For certain samples, it might be desirable to eliminate the component of the reflected energy
which is not diffused by scattering - commonly called the specular component (reflectance
from a mirror is pure specular). While specular reflectance occurs over all angles, the
COLLECTOR II has a provision for lowering it’s contribution to the spectrum - the BLOCKER.
It is not always obvious when the specular component should be excluded. Inorganics or
other samples of high index of refraction might be highly specular, and the BLOCKER would
be used. But one might want to first try grinding the sample to a smaller particle size, or
running the sample in a KBr matrix. It is rarely necessary to exclude the specular component
with KBr diluted samples. In general, if the specular component is excluded, signal-to-noise
will suffer and longer scan times will be required. An MCT detector might even be indicated
to improve the signal-to-noise ratios. The high throughput advantage of the COLLECTOR II
over other DRIFT designs results partly from the large collection angle which can include the
specular energy. In general, don’t remove this component unless you must.
Normally, the BLOCKER must be positioned so that the blade is contacting the surface of the
powder but not embedded deeply into the powder (see Figure 2, below). The powder should
be level with the surface of the cup. Overfill the cup with powder, then scrape a spatula
across the top of the cup (see page 20).
After the cup is filled properly, the BLOCKER should be positioned so that it rests firmly on
the sample cup. If it does not rest firmly on the cup, loosen or tighten the screw on top of the
BLOCKER while pushing down on the blade.
Energy throughput is significantly reduced when using the
BLOCKER. This is due to several factors. Most notably,
samples which are suspected of containing specular
distortions (Restrahlen bands) generally are poor diffuse
reflectors. Although they may exhibit high energy
throughput without the BLOCKER, most of this is specular
energy. At best, this merely dilutes the spectrum. At worst,
the aforementioned distortions result, potentially leading to
spectral misinterpretation.
Blocker
KBr
Diffuse
Reflection
Sample
Figure 2 BLOCKER

7
Collector II
General Information
Diffuse Reflectance Sampling Technique
Specular Reflection
When the infrared beam is focused on the surface of the particulate sample, it can interact
with the sample two ways. First, it may simply reflect off the sample surface in the same way
visible light reflects off a mirror. The phenomenon, called “true specular reflection,” is a
function of the refractive index of the sample.
The diffuse reflectance accessory collects infrared radiation from true specular reflection
along with other reflected light. However, the specular component of the infrared light
reaching the detector is considered an interference, because it does not provided information
about the absorption characteristics of the sample.
Diffuse Reflection
The second way the infrared beam may interact with a particulate sample is to penetrate a
particle then scatter or “diffuse.” Depending on the angle at which it emerges from the
particle, the diffused light may penetrate other particles as it moves through the sample
material or it may simply reflect off their surfaces. Diffused light that travels through and is
partially absorbed by particles of the sample material, contains information about the
absorption characteristics of the sample.
Particles that are highly absorbing may produce totally absorbing peaks in the resulting
spectrum because little energy is released from the sample. Highly absorbing material can
be mixed with a diffusely scattering matrix such as KBr, which lowers absorption and
improves throughput.
This explains the origin of the term “diffuse reflection” and the primary purpose of the diffuse
reflectance accessory.

8Thermo Spectra-Tech
Diffuse Reflectance Sampling Technique
Diffuse Reflectance Spectrum
The goal of diffuse reflectance spectroscopy is to maximize the diffused component, because
it contains information about the absorption characteristics of the sample, and to minimize
the specular component, which causes distortions in the data.
Since it is difficult to determine the absorption characteristics and the refractive index of a
powdered sample just by looking at it, the recommended approach is to try running the pure
powder using a KBr background. If distortions or totally absorbing bands appear in the data
or if the sensitivity is low, you can mix the sample with KBr at the recommended ratio and
collect the spectrum again.
Totally Absorbing Bands
Bands with values below 1% R (above 49 Kubelka-Munk units) are considered totally
absorbing and normally have a flattened or “squared off” end.
Derivative-shaped Bands
One relatively common effect in diffuse reflectance spectroscopy are bands that are inverted
or derivative-like in shape. These distortions called Restrahlen bands are caused by
specular reflection off the sample surface.
General Information
Potassium permanganate undiluted, with
derivative-shaped bands at 919 cm-1. Potassium dichromate undiluted with totally
absorbing bands.

9
Collector II
Beam
Direction
Lock Down Screw
Mattson Mating Plate
(part # 3000-537)
Hold down screws (4)
for Base Plate
Hole for alignment pin
Beam
Direction
Hole for alignment pin
(front of Instrument)
Nicolet 60 Series Baseplate
(part #0099-180)
All Collector II’s are pre-aligned and tested in a FT-IR spectrometer prior to shipment.
Additionally, most versions of the Collector II are shipped with the Baseplate pre-attached to
the accessory for rapid and reproducible installations (as illustrated below). This baseplate
attaches to the floor of your spectrometer sample compartment and provides properly
positioned mounting holes for the Collector II. Therefore, only minor adjustments to the
mirrors should be required to maximize energy throughput. Read all installation and
alignment instructions before proceeding with any adjustments to the optics of your Collector
II.
Remove the baseplate
Locate the four (4) shipping hold down screws (8-32) on the Baseplate of your spectrometer
(if not already removed).
Remove the 4 screws with a slotted head screwdriver.
Remove the Baseplate completely from the sample compartment.
Installation & Alignment
Sample Compartment Baseplate Removal
Note: The accessory with pre-attached baseplate is oriented the same way as the sample
compartment baseplate was before removal.

10 Thermo Spectra-Tech
COLLECTOR II Installation
Installation & Alignment
Record the open beam energy
Record the open beam energy of your spectrometer by monitoring either the throughput
energy number or the height of the centerburst of the interferogram.
Note this value for later use.
Attach foam purge rings
Attach purge rings to both ends of the Collector II.
Place COLLECTOR II in Sample
Compartment
Use the four hold down screws (8-32) that were
removed from the sample compartment to attach
the Collector II baseplate to your spectrometer*.
*Note: See Appendix A for individual
spectrometer mounting requirements and
diagrams.

11
Collector II
COLLECTOR II Installation
Installation & Alignment
Seal Purge Rings
Once the unit is placed in the sample
compartment, adjust the rings until they meet the
the wall of the sample compartment and create a
seal.
Collector II
Purge Cover Sample Compartment
Wall
Install Alignment Mirror
Slide the ellipsoidal mirrors open.
Place the aluminum alignment mirror into the cup
holder.
Slide the ellipsoidal mirrors closed.
Attach hosing
Attach the open end of the plastic hosing
(provided) to the purge nipple on the back of the
Collector II.
For Nicolet systems with purge capabilities:
Attach the other end of the tubing to the socket in
the sample compartment.
For all other instruments: Remove the fitting and
attach the other end of the hose to an external
dry, CO2free air source.

12 Thermo Spectra-Tech
Energy Throughput Validation
When the Collector II is installed, observe the “throughput count” of the FT-IR. Throughput
should be between 30% and 50% of the open beam throughput before the accessory was
installed.
If you are getting this percentage, no further adjustments are necessary and the Collector II
is ready for use. The accessory will provide sufficient energy to permit good signal-to-noise
ratios using a DTGS detector and moderately short acquisition times.
If you are not getting this percentage, the Collector II must be removed from the sample
compartment and the Purge Cover /Purge Insert needs to be detached from the accessory to
access the mirrors for optimal alignment.
COLLECTOR II Installation
Installation & Alignment
Adjust Sample Height/Focus
While monitoring maximum throughput energy
value or the height of the centerburst of the
interferogram, use a 3/32 balldriver to adjust the
screw that positions the alignment mirror for
maximum throughput signal.

13
Collector II
Detach Purge Cover/Purge Insert
The Collector II with its attached baseplate must
be removed from the sample compartment to
access the screws that hold the Purge
Cover/Purge Insert.
Remove the four buttonhead screws that hold the
Purge Cover/Purge Insert in place using a 1/16
balldriver. Two screws are located at the lower
back corners of the accessory and the other two
are located in the front.
The Purge Cover slides straight forward for
removal and straight back for replacement.
Installation & Alignment
Note: The Purge Cover is designed to fit snugly against the walls of the Collector II
accessory. It may be necessary to gently pry the outer walls of the Purge Cover to remove
it.
Install Collector II without Purge
Cover/Purge Insert
Re-install the Collector II and baseplate back into
the sample compartment for re-alignment.
It is not necessary to install the back two screws.
The accessory will have to be removed to replace
the Purge Cover/Purge Insert.
Purge Cover/Purge Insert Removal

14 Thermo Spectra-Tech
Installation & Alignment
Mirror Alignment
M3
M4
M2
M6
M1M7
M5
Adjustment Introduction
The COLLECTOR II is configured at the factory
for your spectrometer.
The COLLECTOR II is also pre-aligned so that
only minor adjustments (tilt and/rotation) of the
mirrors may be necessary.
There are four mirrors to adjust M1, M2, M6, M7
and the sample position.
Adjust the Sampling Position
Open the ellipsoidal mirrors and place the
alignment mirror (face up) on the sample stage.
Using a 3/32 balldriver, adjust the screw so that
the mirror is approximately in the same plane as
the top surface of the Collector II’s top plate.
Adjust Mirror M1
Carefully place a piece of paper in front of Mirror
M2.
Rotate Mirror M1 until the spectrometer’s laser
beam is visible in the center of M2.
Note: Place a piece of paper on edge across the
top plate and mirror to help position the stage.
Note: Be certain that the instrument’s laser
beam is coaxial with the IR beam.

15
Collector II
Mirror Alignment
Installation & Alignment
Check Beam on Alignment Mirror
Leave the OUTPUT ellipsoid mirror open. Close
the INPUT ellipsoid mirror.
Hold a small piece of paper on the surface of the
alignment mirror. The laser beam should be
visible in the center of the alignment mirror. If the
beam is not in the center, rotate Mirror M2. Slide
the OUTPUT ellipsoid closed.
Slide the ellipsoid closed.
Adjust Mirror M6
Carefully place a piece of paper in front of Mirror M7.
Rotate Mirror M6 until the laser beam is visible in the center of M7.
Adjust Mirror M7
Carefully place a piece of paper in front of the exit port to the detector.
Rotate Mirror M7 until the laser beam is visible in the center of the port.
Adjust Mirror M2
Carefully place a piece of paper in front of Mirror
M6.
Rotate Mirror M2 until the laser beam is visible in
the center of M6.
Note: The output is the left ellipsoid for a right to
left beam and the right ellipsoid for a left to right
beam.

16 Thermo Spectra-Tech
Installation & Alignment
Mirror Fine Adjustment
Mirror
Alignment Tool
Either
End of Tool
can be used
Mirror
Mount
Fine-Tune Mirror Rotation
Put the spectrometer in align
mode (throughput, tune
etc.).
Peak the throughput energy
to all the mirrors by rotating
each mirror in the following
order M7, M6, M2 and M1.
Repeat order a second time.

17
Collector II
Installation & Alignment
Mirror Fine Adjustment
Fine-Tune Tilt Adjustment
Test the tilt of the mirror by lightly pressing the mirror mount in each direction noting the
energy count. The tilt of the mirrors is adjusted through the two screws located at the base
of the mirrors. If the energy increases as the mirror is tilted in the direction shown in Figure
3A (below), loosen the front screw and tighten the back screw 1/8” of a turn . If the energy
increases as the mirror is tilted in the direction shown in Figure 3B (below), loosen the back
screw and tighten the front screw 1/8” of a turn (see 3B below). Retest the tilt. When no
further adjustment is needed, carefully tighten the screws without moving the mirror.
When the COLLECTOR II is fully aligned, it may be removed to re-attach the Purge Cover
and Purge Insert and then replaced in the FT-IR sample compartment.
3A 3B
Figure 3 Tilt Adjustment

18 Thermo Spectra-Tech
Installation & Alignment
Purge Cover/Purge Insert Reinstallation
Attach Purge Cover/Purge Insert
After the Collector II is aligned for optimal energy
throughput, remove the accessory from the
compartment and attach the Purge Cover/Purge
Insert.
Reinstall Collector II and Purge Rings
Replace the accessory into the sample
compartment and reseal Purge Rings to the walls
of the spectrometer’s sample compartment (see
instructions on page 9 & 10).
The Collector II is ready to use.
Reattach Purge Hose
Reattach Purge Hose (see instructions on page 9
& 10).
Collector II
Purge Cover Sample Compartment
Wall