Questions tagged [mass-spectrometry]

Mass spectrometry (MS) is an analytical technique which takes advantage of the mass-to-charge ratio of gas-phase ions in order to elucidate the composition of a sample.

Filter by
Sorted by
Tagged with
15
votes
1answer
747 views

Understanding how mass spectroscopy works

I’m trying to get a deeper understanding of how mass spectroscopy works. Most tutorials and textbooks I’ve encountered omit certain details about the process and I’m hoping someone out there who ...
6
votes
2answers
545 views

What is the relative size of the (M+2) peak?

The $(M+1)$ peak is often considered in the high-resolution mass spectra of organic molecules as it reveals the number of carbon atoms in the sample. In general, it is known that the ratio of the size ...
4
votes
1answer
1k views

How does bombarding a molecule with electrons cause ionization?

I am a chemistry student, and my current are of study is mass spectrometry. In the ionization process, atoms are bombarded with electrons, but how does this work? I assume the flow of electrons ...
9
votes
3answers
563 views

How do I figure out how many hydrogens my compound actually has using a mass and NMR spectrum?

Question 3: It said $m/z = 122,$ and $m/z = 124$ is in a $3:1$ ratio, so I figured that meant that chlorine is present. Then I thought $m/z$ was the actual compound's molecular mass. So I used ...
3
votes
3answers
3k views

Mass Spectrum and Molecular Ion peaks [closed]

If a molecule contains four chlorine atoms, how many molecular ion peaks will this compound show in its mass spectrum?
5
votes
3answers
6k views

How to retrieve Dalton value from m/z value?

As I understand, Dalton (Da) is the standard way for representing mass unit. As for $m/z$, which is a specific notation for mass spectrometry, quoting for wikipedia: This notation eases data ...
4
votes
3answers
6k views

Could someone please explain the difference between m/z and m/e in mass spectroscopy

The definition: The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio ...
3
votes
2answers
1k views

Fragmentation of phenyl radical cations in mass spectrometry

What are the main fragmentation pathways and products of a phenyl radical cation in mass spectrometry ? I notice sometimes that there's a m/z = 51 peak after the m/z = 77 for phenyl radical cation; I ...
3
votes
1answer
1k views

What are compounds with the same mass called?

It may be that the answer is just "no" and that's why I can't find it, but is there any common name for compounds with the same mass? I'm thinking in the context of mass spectrometry where these ...
3
votes
1answer
2k views

Why is the molecular peak not observed in the mass spectrum of 2,2-dimethylbutane?

Why isn't the molecular weight of 2,2-dimethylbutane on the mass spectrum? I can tell that a $\ce{-CH3}$ group is removed just by the math, but I do not know the reason why. The molecular weight is 86 ...
2
votes
1answer
104 views

Why does the heat of formation of organic radicals and positive ions decrease with their size and degree of branching at the radical or ionic site?

I am currently studying the textbook Mass Spectrometry, third edition, by Jürgen H. Gross. Chapter 2.4.3 Bond Dissociation Energies and Heats of Formation says the following: The heat of formation ...