Tabular Mass Spectrum of Ethanol

Chapter 2 of this book describes the mass spectra produced by El ionization and how the spectral peak pattern relates to molecular structure. Chapter 3 describes in detail the use of high-resolution and accurate mass measurement to determine elemental compositions of ions as an aid to identifying unknown substances. Chapter 4 provides an introduction to some of the more modern techniques used to extend the usefulness of mass spectrometry into high molecular weight and more polar substances. 

The reaction scheme shown in Equation 2.1 depicts how electron (El) ionization employs a high-energy electron beam to excite molecules M in the vapor state to high electronic and vibrational energy levels M. When enough energy is supplied to a molecule, an electron is ejected to produce a positively charged species M+. This is termed the molecular ion. 

When the electron energy is raised above the minimum required to ionize the molecule, the molecular ions will be more apt to fragment. Electron energies on the order of 50 to 70 electron volts (eV) are generally used in routine mass spectrometric tests. 

Make a list of those ions formed from ethane that have abundances greater than 10 percent of that of the most abundant ion. 

A molecular ion is the ion formed by the simple loss of one electron from a molecule. The most fundamental structural information provided by a mass spectrum is the molecular weight of a compound, as defined by the mass of the molecular ion. 

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