Excel Charting: Detailed Absorbance vs Wavelength Plotting.

Written by Kasper Langmann

The world of data analysis is vast and complex, and one of the most essential tools in this field is Microsoft Excel. Excel offers a plethora of functionalities that can be utilized to analyze and visualize data in a comprehensive manner. One such functionality is charting, which allows users to create a variety of charts to represent data graphically. This article will delve into the specifics of creating an absorbance vs wavelength plot in Excel, a common requirement in fields such as spectroscopy and chemistry.

Understanding Absorbance and Wavelength

Before diving into the specifics of creating the plot, it’s crucial to understand the concepts of absorbance and wavelength. In the field of spectroscopy, absorbance refers to the quantity of light absorbed by a substance. It is a dimensionless quantity that is typically measured at different wavelengths.

Wavelength, on the other hand, is a term used to describe the distance between two successive crests or troughs in a wave. In the context of spectroscopy, it refers to the wavelength of light that is absorbed or transmitted by a substance. The relationship between absorbance and wavelength is often represented graphically in the form of an absorbance vs wavelength plot.

Creating an Absorbance vs Wavelength Plot in Excel

Step 1: Inputting the Data

The first step in creating an absorbance vs wavelength plot in Excel is to input the data. This data is typically obtained from a spectrophotometer, a device used to measure absorbance at different wavelengths. The data should be input into two columns: one for wavelength and one for absorbance. It’s important to ensure that the data is accurate and free from errors, as this will affect the quality of the plot.

Once the data has been input, it’s a good idea to sort it in ascending order based on the wavelength. This can be done by selecting both columns, clicking on the ‘Data’ tab, and then clicking on ‘Sort’. In the dialog box that appears, choose ‘Sort by’ the wavelength column and ‘Order’ as ‘Smallest to Largest’.

Step 2: Creating the Plot

With the data input and sorted, the next step is to create the plot. This can be done by selecting the data and then clicking on the ‘Insert’ tab. In the ‘Charts’ group, click on ‘Scatter’ and then choose ‘Scatter with Straight Lines’. This will create a basic scatter plot with the wavelength on the x-axis and the absorbance on the y-axis.

At this point, the plot will be quite basic and may not accurately represent the data. To improve the plot, it’s necessary to adjust the axes, add a title, and format the plot. These steps will be covered in the following sections.

Step 3: Adjusting the Axes

The next step in creating an absorbance vs wavelength plot in Excel is to adjust the axes. This involves setting the minimum and maximum values for the x-axis (wavelength) and the y-axis (absorbance). The minimum and maximum values should be chosen based on the range of the data. For example, if the wavelength data ranges from 200 to 800, the minimum and maximum values for the x-axis could be set to 200 and 800, respectively.

To adjust the axes, click on the axis that you want to adjust, right-click, and then choose ‘Format Axis’. In the dialog box that appears, enter the minimum and maximum values in the appropriate fields. Repeat this process for the other axis.

Step 4: Adding a Title and Formatting the Plot

The final step in creating an absorbance vs wavelength plot in Excel is to add a title and format the plot. The title should clearly indicate what the plot represents. For example, a suitable title could be ‘Absorbance vs Wavelength’. To add a title, click on the plot, then click on the ‘Chart Tools’ tab, then ‘Layout’, and then ‘Chart Title’. Choose ‘Above Chart’ and then type the title in the box that appears.

Formatting the plot involves adjusting the color, size, and style of the plot to make it more visually appealing. This can be done by clicking on the plot, then clicking on the ‘Chart Tools’ tab, then ‘Format’, and then choosing the desired options. For example, you could choose to display the data points as circles, change the color of the line to blue, and increase the size of the title.

Conclusion

Creating an absorbance vs wavelength plot in Excel may seem daunting at first, but with a little practice, it becomes quite straightforward. The key is to understand the concepts of absorbance and wavelength, input and sort the data correctly, create a basic plot, adjust the axes, add a title, and format the plot. By following these steps, you can create a detailed and accurate absorbance vs wavelength plot that can be used for data analysis in fields such as spectroscopy and chemistry.

Remember, Excel is a powerful tool for data analysis and visualization, but it’s only as good as the data you input. Always ensure that your data is accurate and free from errors, and don’t be afraid to experiment with different chart types and formatting options to find the one that best represents your data.