Bending, scissoring and rotating motions are only seen as third or fourth overtones and are mostly lost in the baseline. spectr.

[Natuli]

Помогите, пожалуйста, перевести "Bending, scissoring and rotating motions" и "pure bands" - какие полосы?, если речь идет о БИК спектроскопии
The bandwidth, on the other hand, increases with each consecutive overtone as a result of increased anharmonicity. Thus, only vibrations that involve bonds that have strong absorptions in the fundamental Mid-IR range, such as C-H, N-H and O-H, can be readily distinguished in the NIR region. Bending, scissoring and rotating motions are only seen as third or fourth overtones and are mostly lost in the baseline. In the NIR region few pure bands exist and little structural detail can be determined visually.