Normalization by Area

Table of contents

  1. Introduction
  2. How to use
  3. Behavior
  4. Method
  5. References

Introduction

Normalization by Area rescales each spectrum by its integrated area so spectra with different total signal levels can be compared.

How to use

To normalize your data by area:

  1. Upload data and select the spectra to be processed.
  2. Navigate to the sidebar and turn on the “Normalization” toggle.
  3. Select “Normalize by area” from the drop-down menu.
  4. Click “Process” to update the display.

Behavior

Normalizing by area is good for standardizing data with different measurement conditions. This method rescales each data point so that the total area under the spectrum curve is 1. The area is calculated using a trapezoidal sum. Mathematically, the normalized intensity $S(x)$ at Ramanshift $x$ is determined by:

\[S(x)=\frac{I(x)}{\sum_{i=1}^n \frac{1}{2}\left(I(x_i)+I(x_{i-1})\right)\left(x_i-x_{i-1}\right)}\]

where $I(x)$ is the intensity observed at Ramanshift $x$, and $n$ is the number of Ramanshift values observed for a given spectrum.

Method

The implementation divides each selected spectrum by its trapezoidal area over Raman shift:

\[I_{\text{norm}}(x)=\frac{I(x)}{\int I(x)\,dx}\]
Parameter Tunable or fixed Implementation
Method choice Tunable Selected as Normalize by area
Integration Fixed Trapezoidal area using the Raman shift column

References

  1. SpectraGuru implementation, self-implemented area normalization.

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