2012 Product Catalogue

Specac Product Catalogue 2012 | Golden Gate Single Reflection Diamond ATR
Reproducibility and Sensitivity of the Golden Gate
Single Reflection ATR System
0.4
1.2
0.35
0.3
Lacquer on Copper Wire
Paper Sample
Wool/Polymer Cloth
Sweetner (powder)
Nylon Monofilament
Single Human Hair
1
0.8
0.25
Absorbance
0.2
Absorbance
0.6
0.15
0.4
0.1
Hard Red Polymer
Soft Polymer Pellet
Peet Tubing
0.2
Hard ABS Pellet
Soft Polyurethane
0.05
Polythene Sheet
PTFE Sheet
Irregular Peet Pellet
0
0
20 40 60 80 100 120 140 160 180 200
Applied Load (lbs)
0
0
20 40 60 80 100 120 140 160 180 200
Applied Load (lbs)
Typical competitive ATR pressure range
Typical competitive ATR pressure range
Golden Gate pressure range
Golden Gate pressure range
The effect of load on ATR sensitivity
A key feature of the Golden Gate Single
Reflection ATR System is the outstanding contact
achievable between solid samples and the
diamond crystal.
For many sample types (particularly powders and
fibers), as the load is applied to the sample and
optical contact between the diamond and the
sample increases, the intensity of the
absorbance bands also increase. In other words,
increasing the load increases the sensitivity. The
Golden Gate gives the highest load capability of
any commercial diamond ATR (over 180 lbs) and
the diagrams above illustrate how that impacts
sensitivity for a variety of sample types.
For softer samples, such as polymers, a similar
effect is seen. However, once the sample has
fully contacted the ATR surface, the absorbance
stops increasing with increasing pressure.
In order to achieve the best measurement
repeatability and reproducibility for these
samples, the instrument should ideally apply a
load above the “knee” of the curve where the
absorbance becomes much less sensitive to
load. The diagram above right illustrates some
measurements for typical samples. Note how the
harder sample types need a higher load to reach
this ideal situation - and very often the Golden
Gate is the only product that can do it.
0.7
0.5
0.6
Absorbance / a.u.
0.4
0.3
0.2
0.1
Water
Absorbance / a.u.
0.5
0.4
0.3
0.2
0.1
Polyethylene glycol (PEG 600)
0.0
0.0
3900 3600 3300 3000 2700 2400 2100 1800 1500 1200 900 600
3900 3600 3300 3000 2700 2400 2100 1800 1500 1200 900 600
Wavenumber cm -1
Wavenumber cm -1
1.2
0.40
0.35
Absorbance / a.u.
1.0
0.8
0.6
0.4
0.2
Polydimethylsiloxane (PDMS)
Absorbance / a.u.
0.30
0.25
0.20
0.15
0.10
0.05
Hexadecane (C 16 H 34 )
0.0
0.00
3900 3600 3300 3000 2700 2400 2100 1800 1500 1200 900 600
Wavenumber cm -1
-0.05
3900 3600 3300 3000 2700 2400 2100 1800 1500 1200 900 600
Wavenumber cm -1
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