Final answer:
In IR spectroscopy, the peaks on an infrared spectrum point downwards, indicating areas of strong absorption. This is opposite to UV-vis spectroscopy, where peaks typically point upwards. IR spectrum uses wavenumber in cm⁻¹ whereas UV-vis employs wavelengths measured in nanometers.
Step-by-step explanation:
In infrared (IR) spectroscopy, the peaks on an infrared spectrum typically point downwards, contrary to what one might expect. This is because the graph represents transmittance for every wavelength, and the downward 'peaks' indicate regions of strong absorption by the sample being analyzed. IR spectra are unique in displaying the absorbance peaks as downward-pointing rather than upward-pointing, which may seem counterintuitive but is standard in the field. Additionally, the convention in IR spectroscopy is to report wavenumber values (in cm⁻¹) on the x-axis, rather than wavelengths (in meters) or frequency (hertz).
Comparatively, in UV-visible (UV-vis) spectroscopy, the baseline is situated at the bottom of the graph with peaks actually pointing upwards and wavelengths are typically measured in nanometers (nm). These different conventions in spectral presentations reflect the practices established in each field of spectroscopy.