ATRMAX II Description:

The ATRMax II is a high throughput, variable angle horizontal ATR accessory. The design employs a unique optical layout which enables samples to be analyzed over a range of incident angles from 25 to 65 degrees. Variable angle of incidence provides experimental control over the depth of penetration of an IR beam into the sample and the number of beam reflections in the ATR crystal. The ATRMax can be used for depth profiling studies where spectral composition can be analyzed relative to depth of penetration as the angle of incidence is changed.

Selectable angle of incidence

• 3-12 reflections

• Flat and trough plates

• Motorized and temperature controlled options

A Quick Reflection on Multiple Reflection Attenuated Total Reflectance:

Multiple Reflection Attenuated Total Reflectance (MRA-ATR) is a variant of ATR spectroscopy that involves multiple internal reflections of the infrared (IR) beam at the interface between the ATR crystal or prism and the sample. In contrast to single reflection ATR, where only one internal reflection occurs, MRA-ATR utilizes multiple reflections to enhance sensitivity and increase the effective sampling depth.

Key features and considerations of Multiple Reflection Attenuated Total Reflectance (MRA-ATR) include:

1. Enhanced Sensitivity: With each internal reflection, the IR beam penetrates deeper into the sample, increasing the effective path length and sensitivity compared to single reflection ATR. This makes MRA-ATR suitable for samples with lower concentrations or weaker absorptions.

2. Increased Sampling Depth: MRA-ATR provides information from a greater depth within the sample compared to single reflection ATR. The depth of penetration depends on the number of reflections and the refractive indices of the ATR crystal and the sample.

3. Signal-to-Noise Ratio: MRA-ATR can yield higher signal-to-noise ratios compared to single reflection ATR, making it more suitable for weakly absorbing samples.

4. Sample Homogenization: As the IR beam penetrates deeper into the sample during multiple reflections, it tends to homogenize the sample, effectively averaging over a larger volume. This can be advantageous when analyzing heterogeneous samples.

5. Sample Thickness Consideration: In MRA-ATR, the sampling depth increases with the number of reflections. However, this also means that MRA-ATR may become less surface-sensitive and less suitable for studying very thin surface layers.

6. Sampling of Bulk Properties: MRA-ATR is useful for analyzing the bulk properties of samples, making it applicable to a wide range of solid and liquid samples.

7. Experimental Setup: The experimental setup for MRA-ATR is similar to single reflection ATR, with the ATR crystal or prism, the sample, and the detector. The main difference lies in the number of reflections the IR beam undergoes.

8. Data Analysis: When dealing with MRA-ATR data, researchers need to consider the impact of multiple reflections on the spectral features. The data analysis may involve deconvolution or other correction methods.

MRA-ATR is commonly employed in various fields, including chemistry, materials science, pharmaceuticals, and environmental analysis. It provides valuable information about the composition, structure, and properties of a wide range of samples.

The choice between single reflection ATR and multiple reflection ATR depends on the specific research objectives, sample properties, and the required sensitivity and depth of analysis. Researchers often choose the ATR configuration that best suits their needs to obtain accurate and informative spectroscopic results.