# 19.1.10.2 Peak Analyzer, Baseline Mode Page

Use the Baseline Mode page to create a baseline.

• Menu Command: Analysis: Peaks and Baseline: Peak Analyzer: Open Dialog
• Window Types: Workbook, Graph

## Dialog Theme

Dialog Theme See Peak Analyzer Themes.

## Baseline Mode

There are between four and eight Baseline Modes, depending upon your selected Goal. Some Baseline Modes (e.g. User Defined) create additional controls on this page, while others add a page to the Wizard Map.

Baseline Mode Description
Constant Baseline is a horizontal line where Y= Constant. Options include Minimum, Maximum, Mean and Median of the data, and Custom for editing the Y value.
User Defined You can create a user defined baseline using one of five methods for finding anchor points:
• 2nd Derivative (zeroes): Use the 2nd Derivative (zeroes) method for baseline detection.
• 1st Derivative and 2nd Derivative: Use the 1st Derivative and 2nd Derivative method for baseline detection (this method is more powerful when the baseline is approximately constant).
• Use Script to Search: Use pre-defined LabTalk script to customize the method of auto finding anchor points. See this example for details.
• Use Existing Dataset: Use an existing dataset as the XY coordinates of baseline anchor points.
• Dataset: You can select a pair of XY columns from Dataset Browser which will display after clicking button. You can also input range notation eg., (A,C), (2,3), to refer to relative columns in the worksheet where target dataset locates. Note that such range notation only works for data from worksheet rather than graph.
• Current Number of points: Read only, display the current number of anchor points.
• 2nd Derivative (peaks): Use the 2nd Derivative (peaks) method for baseline detection (this method is more recommended if many data points' 2nd derivative approaches to 0).
Use Existing Dataset Use an existing dataset as the XY coordinates of baseline anchor points. You can input range notation eg., (A,C), (2,3), to refer to relative columns in the worksheet where target dataset locates. Note that such range notation only works for data from worksheet rather than graph.

Offset Baseline: Enter a value in this text box to offset the baseline.

XPS The Peak Analyzer will allow you to define an X-ray photoemission spectrum special baseline. For more details, please refer to the Peak Analyzer, XPS Baseline Page.
None (Y=0) The Peak Analyzer will use Y=0 as baseline.
Min&Max When detecting positive peaks, minimum value in selected data range will be used as baseline; whereas, maximum value will be used as baseline for detecting negative peaks. Note that this option is only available when Goal is Find Peaks.
End Points Weighted Create a smoothed curve as baseline using data points from two ends of the input data.

Note: This method depends heavily on the selection of end points. You should select the end points fraction very carefully.

Straight Line Create a straight line as baseline by setting the Y intercept and slope. The default value of A(Intercept) and B(Slope) is obtained by connecting the two end points of the data; you can clear the Auto check box to enter the desired values in the edit boxes.

Please note, the digits of default values of A(Intercept) and B(Slope) is decided by the digits settings in the Numeric Format tab of Options dialog.

Asymmetric Least Squares Smoothing Create a smooth baseline based on Asymmetric Least Squares (ALS) correction method. For more details, please refer to the Peak Analyzer, Asymmetric Least Squares Smoothing Baseline Page.

### User-defined Anchor Points Options

When Baseline Mode = User Defined, these controls are added to the page.