  Electronic transitions in molecules due to the absorption or emission of
light is a complex quantum mechanical process. Their study plays an important
role in the design of novel materials. A common yet challenging task in the
study is to determine the nature of electronic transitions, namely which
subgroups of the molecule are involved in the transition by donating or
accepting electrons, followed by an investigation of the variation in the
donor-acceptor behavior for different transitions or conformations of the
molecules. In this paper, we present a novel approach for the analysis of a
bivariate field and show its applicability to the study of electronic
transitions. This approach is based on two novel operators, the continuous
scatterplot (CSP) lens operator and the CSP peel operator, that enable
effective visual analysis of bivariate fields. Both operators can be applied
independently or together to facilitate analysis. The operators motivate the
design of control polygon inputs to extract fiber surfaces of interest in the
spatial domain. The CSPs are annotated with a quantitative measure to further
support the visual analysis. We study different molecular systems and
demonstrate how the CSP peel and CSP lens operators help identify and study
donor and acceptor characteristics in molecular systems.
