What characteristic of mass spectrometry makes it effective for identifying isotopes?

The effectiveness of mass spectrometry in identifying isotopes is primarily attributed to its ability to analyze the mass-to-charge ratio of ions. Isotopes of the same element have the same number of protons but different numbers of neutrons, resulting in different atomic masses. When a sample is ionized in a mass spectrometer, the ions are accelerated and then sorted based on their mass-to-charge ratios. This separation enables the detection of different isotopes as distinct peaks on a mass spectrum. Each isotope will produce a different peak corresponding to its specific mass, which allows for precise identification and quantification.

The other characteristics mentioned do not play a role in identifying isotopes. For instance, measuring optical properties pertains to techniques like spectroscopy, which does not provide information about isotopic composition. Monitoring chemical reactions in real-time is useful for kinetic studies but does not help in distinguishing isotopes. Lastly, determining temperature is unrelated to the mass spectroscopy process or to the identification of isotopes. Therefore, the ability to analyze mass-to-charge ratios is what makes mass spectrometry a powerful tool for isotope identification.