Aztecwave如何实现准确的结果

In this interview AzoM talks to Dr Rosie Jones about the AZtecWave spectrometer, its features, applications, and its role in obtaining accurate results.

您能解释一下波光谱仪是什么，在哪些行业中主要使用了什么？

The Wave spectrometer is an instrument for conducting elemental analysis by wavelength dispersive spectrometry on a scanning electron microscope. The WDS technique works on solid samples and can quantify the elements present in a sample at specific micron-size points or map the distribution of elements across a sample surface. In terms of where it is used, the Wave spectrometer is used in both industry and academia. It is primarily used in materials, metallurgy, geology, automotive and aerospace, and the energy sector. However, it can be useful in any field where the elemental composition of solid samples needs to be determined, particularly where elements are present in trace concentrations and these need to be accurately quantified.

Image Credit: Oxford Instruments NanoAnalysis

Elemental analysis is typically carried out on the SEM using EDS, so how is WDS different and why would you want to add it?

能源分散光谱法（EDS）是一种用于SEM组成分析的既定技术。

EDS对于确定元素组成是快速有效的，但是它确实有一些局限性可以使用WD来克服。

EDS根据电子束与其相互作用时生成的特征X射线信号确定样品中存在的元素。不同的元素具有具有各种能量的特征X射线，这些能量以EDS光谱中的峰出现。

One limitation of EDS analysis is that some characteristic X-rays have very similar energies. With the spectral resolution of EDS, these occur as overlapping peaks in the EDS spectrum. For example, the Ti Kβ peak overlaps with the V Kα peak, making it difficult to accurately measure these elements if both appear in a sample. WDS has a higher spectral resolution, making it possible to resolve overlaps in the EDS spectrum with WDS, such as Ti Kβ and V Kα.

Image Credit: Oxford Instruments NanoAnalysis

您能解释一下波长 - 分散光谱仪的不同样式是什么？

There are two styles of wavelength dispersive spectrometers – Rowland circle and parallel beam. The primary difference between these two styles is geometry. The Wave spectrometer has Rowland circle geometry, the same geometry style used on an electron microprobe – the dedicated instrument for WDS analysis.

What advantages does the Rowland circle geometry of the Wave spectrometer bring?

The Wave spectrometer, which has a 210 mm Rowland circle and is fully focussing, delivers the best spectral resolution available. The resolution that can be achieved is approximately 10x higher than energy dispersive spectrometry (EDS) and 2x higher than what can be achieved with a parallel beam WD spectrometer.

这意味着波光谱仪可用于分离EDS或其他光谱仪无法分离的特征X射线峰。因此，波光谱仪为元素识别带来了确定性，并更准确地量化受峰重叠影响的元件。波光谱仪的较高光谱分辨率给出了较高的峰值与背景比，因此具有较低的检测极限。波光谱仪可以准确检测并测量痕量元素（<1000 ppm）。

How does the Wave spectrometer offer a higher spectral resolution?

This is delivered through a combination of the physical geometry and size of the Rowland circle, and the use of a variable entrance slit positioned in front of the X-ray counters. The entrance slit optimizes the resolution and a narrower slit width increases the resolution that can be achieved.

是什么使牛津仪器波光谱仪的定位设计与众不同？

The Wave spectrometer is positioned at an inclined angle on the SEM, not vertical, as is used on electron microprobes (i.e. EPMA). Having the spectrometer at an inclined angle on the SEM broadens the plane of the Rowland circle and brings position advantages to the sample in the SEM.

What advantages does this provide?

样品高度不必仔细地定位即可生成准确的定量数据。样品高度可以变化到约+/- 0.5毫米，而不会从罗兰圆圈移出样品。因此，对计数速率没有影响，高度略有变化。因此，可以简单地使用SEM上的辅助电子图像来充分地定位样品的高度。

样本设置与其他替代方案相比如何？

It ultimately makes the sample set-up quicker and easier. Parallel beam WD spectrometers often have to go through focussing routines to ensure that the correct geometry is achieved for each element, lengthening analysis time. The sample must be very carefully positioned and focused on electron microprobes using the optical image, which also takes time.

为什么WDS比ED慢，为什么这很重要？

Like EDS, WDS utilizes the X-ray signal generated by bombarding a solid sample with a beam of high-energy electrons. Unlike EDS, WDS is based on Bragg’s Law of diffraction and therefore can only measure X-rays of a single wavelength or energy at a time.

On the other hand, EDS measures all X-ray energies simultaneously, making it much faster for multi-element samples.

EDS typically has a higher solid angle and count rate, making EDS analysis quicker than WDS analysis. This is why we have designed our system and software so that users can simultaneously perform and combine EDS and WDS analysis – EDS can be used to quickly and accurately analyze major elements and those unaffected by peak overlaps.

WD可以仅在需要的地方使用，以测量轨迹元素或受EDS频谱中峰重叠影响的元素。EDS和WDS分析结果自动合并在我们的AZTECWAVE软件中。

Image Credit: Oxford Instruments NanoAnalysis

What makes the Oxford Instruments Wave spectrometer easy to use?

The Wave spectrometer is fully controlled using the AZtecWave software. Because of some of the complexity involved with setting up WDS analysis, we have designed the AZtecWave software with a strong focus on ease of use. The user does not have to be an expert to use the system and achieve accurate results. For example, we have designed unique workflows not just for EDS or WDS analysis but to effectively combine both. We have also developed software technology that automatically optimizes the collection settings, instead of just applying default values or relying on inputs from the user that require expertise.

Image Credit: Oxford Instruments NanoAnalysis

消费者可以利用的系统的一些易用功能是什么？

There are lots of ease-of-use features in the AZtecWave software. A significant development we have introduced to AZtecWave is the software technology I have just mentioned. This automatically takes the live input from both the SEM and EDS detector and uses it to automatically set the collection settings for the WDS analysis. For example, AZtecWave will automatically pick the most appropriate X-ray line and crystal, set the peak and background counting times to achieve a certain level of error on the analysis, and automatically set the background positions to avoid any interferences. These are difficult settings for a user to set without a good level of prior knowledge.

AZtecWave removes the complexity for the novice user, but it remains flexible for the expert user with options for manual selections/adjustments.

其他易用功能包括：

• 用于将WD与EDS分析相结合的指导工作流程
• Step-by-step instructions in the user interface throughout the setup and data collection
• 内置光谱仪性能检查以确保在数据采集之前设置并正确执行波光谱仪
• 帮助可以轻松从软件访问的视频以获取其他指导

Image Credit: Oxford Instruments NanoAnalysis

您能否给出特定的申请示例，说明使用了哪些WD和Aztecwave的目的？

WDS和Aztecwave可以在矿物，陶瓷和金属等实心样品中定量测量主要，次要和微量元素。

In geology, the trace element concentration of minerals can be used to interpret how they formed. In metallurgy, trace concentrations of elements such as carbon, sulfur, and boron can profoundly impact the metal's properties; therefore, it is important to quantify them accurately.

My colleague has recently carried out some work using WDS and AZtecWave to investigate the concentrations of dopants in semiconductor samples (https://www.oxinst.com/blogs/wds-sem-approach-for-studying-doping-in-semiconductors?business=nanoanalysis&sbms=nanoanalysis).

The analysis of rare earth elements (REE) is another important application that can be addressed using WDS and AZtecWave. The REE have numerous peak overlaps in the EDS spectrum, but these can be resolved using WDS. REE are increasingly being used in existing and developing technologies, such as fuel cells, electric vehicles, and batteries.

About Dr Rosie Jones