question: How do we know what the guts of an atom are? How are we able to count protons etc.?
comment: Have you ever played with the toy with the hundreds of metal rods on one side and the other side has a glass square to prevent the rods from spilling off? When you pressed you hand on the rod side it would push the rods to the glass side revealing the imprint of your hand. We have machines that do that and reveal the image of the atomic structure.
passages: A wide range of instrumental techniques are employed in nuclear forensics. Radiometric counting techniques are useful when determining decay products of species with short half-lives. However, for longer half-lives, inorganic mass spec is a powerful means of carrying out elemental analysis and determining isotopic relationships. Microscopy approaches can also be useful in characterization of a nuclear material.
  
  Section::::Analysis.:Counting Techniques.
   BULLET::::- Optical emission spectrometry, OES
  
  BULLET::::- Neutron activation analysis, NAA
  
  BULLET::::- Atomic absorption spectroscopy AAS
  
  BULLET::::- X-ray fluorescence XRF
  
  BULLET::::- PIXE - particle induced x-ray emission
  
  BULLET::::- Electron microprobe
  
  BULLET::::- X-ray diffraction
  
  BULLET::::- Cathodoluminescence
  
  BULLET::::- Raman spectroscopy
  
  Section::::Techniques.:Agent-based modeling.
   BULLET::::- Nuclear chemistry is the study of how subatomic particles come together and make nuclei. Modern Transmutation is a large component of nuclear chemistry, and the table of nuclides is an important result and tool for this field.
  
  BULLET::::- Organic chemistry is the study of the structure, properties, composition, mechanisms, and reactions of organic compounds. An organic compound is defined as any compound based on a carbon skeleton.
   To qualitatively determine which elements exist in a sample, the methods are mass spectrometric atomic spectroscopy, such as inductively coupled plasma mass spectrometry, which probes the mass of atoms; other spectroscopy which probes the inner electronic structure of atoms such as X-ray fluorescence, particle-induced X-ray emission, X-ray photoelectron spectroscopy, and Auger electron spectroscopy; and chemical methods such as the sodium fusion test and schöniger oxidation
  
  Section::::Analysis of results.
   Section::::Spinout areas.:Uses within geology, biology and forensic science.
  
  Cosmogenic isotopes are formed by the interaction of cosmic rays with the nucleus of an atom. These can be used for dating purposes and for use as natural tracers. In addition, by careful measurement of some ratios of stable isotopes it is possible to obtain new insights into the origin of bullets, ages of ice samples, ages of rocks, and the diet of a person can be identified from a hair or other tissue sample. (See Isotope geochemistry and Isotopic signature for further details).
  
  Section::::Spinout areas.:Uses within geology, biology and forensic science.:Biology.
   BULLET::::- 1913 William Henry Bragg and William Lawrence Bragg work out the Bragg condition for strong X-ray reflection
  
  BULLET::::- 1913 Henry Moseley shows that nuclear charge is the real basis for numbering the elements
  
  BULLET::::- 1913 Niels Bohr presents his quantum model of the atom
  
  BULLET::::- 1913 Robert Millikan measures the fundamental unit of electric charge
  
  BULLET::::- 1913 Johannes Stark demonstrates that strong electric fields will split the Balmer spectral line series of hydrogen
  
  BULLET::::- 1914 James Franck and Gustav Hertz observe atomic excitation
  
  BULLET::::- 1914 Ernest Rutherford suggests that the positively charged atomic nucleus contains protons
   BULLET::::- History of radiochemistry – history of the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to a substance being described as being inactive as the isotopes are stable).
  
  BULLET::::- History of organic chemistry – history of the study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of carbon-based compounds, hydrocarbons, and their derivatives.
   BULLET::::- 1909 Ernest Rutherford and Thomas Royds demonstrate that alpha particles are doubly ionized helium atoms
  
  BULLET::::- 1911 Ernest Rutherford explains the Geiger–Marsden experiment by invoking a nuclear atom model and derives the Rutherford cross section
  
  BULLET::::- 1911 Jean Perrin proves the existence of atoms and molecules with experimental work to test Einstein's theoretical explanation of Brownian motion
  
  BULLET::::- 1911 Ștefan Procopiu measures the magnetic dipole moment of the electron
  
  BULLET::::- 1912 Max von Laue suggests using crystal lattices to diffract X-rays
  
  BULLET::::- 1912 Walter Friedrich and Paul Knipping diffract X-rays in zinc blende
   Section::::Analysis.:Mass Spectrometry.
  
  Mass spec techniques are essential in nuclear forensics analysis. Mass spec can provide elemental and isotopic information. Mass spec also requires less sample mass relative to counting techniques. For nuclear forensic purposes it is essential that the mass spectrometry offers excellent resolution in order to distinguish between similar analytes, e.g. U and U. Ideally, mass spec should offer excellent resolution/mass abundance, low backgrounds, and proper instrumental function.
  
  Section::::Analysis.:Mass Spectrometry.:Thermal Ionization MS.
   Section::::What it can measure.
  
  In soft matter research the structure of macromolecular objects is often investigated by small angle neutron scattering, SANS. 
  
  The exchange of hydrogen with deuterium in some of the molecules creates scattering contrast between even equal chemical species. The SANS diffraction pattern—if interpreted in real space—corresponds to a snapshot picture of the molecular arrangement. Neutron spin echo instruments can analyze the inelastic broadening of the SANS intensity and thereby analyze the motion of the macromolecular objects.
   Whilst the uncertainty in the atomic mass computed by time-of-flight methods in atom probe is sufficiently small to allow for detection of individual isotopes within a material this uncertainty may still, in some cases, confound definitive identification of atomic species. Effects such as superposition of differing ions with multiple electrons removed, or through the presence of complex species formation during evaporation may cause two or more species to have sufficiently close time-of-flights to make definitive identification impossible.
  
  Section::::History.
  
  Section::::History.:Field ion microscopy.
   Section::::Measurement techniques.
  
  In the last 70 years various techniques for measuring at nanoscale have been developed. Most of them based on some physical phenomena observed on particle interactions or forces at nanoscale. Some of the most commonly used techniques are Atomic Force Microscopy, X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, High Resolution Transmission Electron Microscopy, and Field Emission Scanning Electron Microscopy.
   With the exception of flames and graphite furnaces, which are most commonly used for atomic absorption spectroscopy, most sources are used for atomic emission spectroscopy.
   BULLET::::- History of radiochemistry – history of the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to a substance being described as being inactive as the isotopes are stable).
  
  BULLET::::- History of organic chemistry – history of the study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of carbon-based compounds, hydrocarbons, and their derivatives.
   Section::::Basic NMR techniques.:Sample handling.
   Section::::Techniques.
  
  Single particle analysis can be done on both negatively stained and vitreous ice-embedded CryoTEM samples. Single particle analysis methods are, in general, reliant on the sample being homogeneous, although techniques for dealing with conformational heterogeneity are being developed.
  
  Images (micrographs) collected on film are digitized using high-quality scanners, although increasingly electron microscopes have built-in CCD detectors coupled to a phosphorescent layer. The image processing is carried out using specialized software programs (for instance ), often run on multi-processor computer clusters. Depending on the sample or the desired results, various steps of two- or three-dimensional processing can be done.
   BULLET::::- History of radiochemistry – history of the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes (often within radiochemistry the absence of radioactivity leads to a substance being described as being inactive as the isotopes are stable).
  
  BULLET::::- History of organic chemistry – history of the study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of carbon-based compounds, hydrocarbons, and their derivatives.
   Commonly encountered techniques are:
  
  BULLET::::- X-ray crystallography: This technique allows for the 3D determination of molecular structures.
  
  BULLET::::- Dual polarisation interferometer: This technique measures the conformation and conformational change of molecules.
  
  BULLET::::- Various forms of spectroscopy
  
  BULLET::::- Ultraviolet-visible spectroscopy: Historically, this has been an important tool, since many inorganic compounds are strongly colored
   This method is especially useful, because it can be fully automated to find uranium particles in a sample of many million particles in a matter of hours. Particles of interest can then be imaged and further analyzed with very high isotopic precision.
  
  Section::::Analysis.:Additional Nuclear Forensic Methods.
  
  Numerous additional approaches may be employed in the interrogation of seized nuclear material. In contrast to previously mentioned analysis techniques, these approaches have received relatively low attention in recent years in terms of novel advancement, and, typically, require greater quantities of sample.
  
  Section::::Analysis.:Additional Nuclear Forensic Methods.:Scanning electron microscope.
   The history of mass spectrometry has its roots in physical and chemical studies regarding the nature of matter. The study of gas discharges in the mid 19th century led to the discovery of anode and cathode rays, which turned out to be positive ions and electrons. Improved capabilities in the separation of these positive ions enabled the discovery of stable isotopes of the elements. The first such discovery was with the element neon, which was shown by mass spectrometry to have at least two stable isotopes: Ne (neon with 10 protons and 10 neutrons) and Ne (neon with 10 protons and 12 neutrons). Mass spectrometers were used in the Manhattan Project for the separation of isotopes of uranium necessary to create the atomic bomb.
   Section::::Uses and capabilities.
  
  XPS is routinely used to determine:
  
  BULLET::::- What elements and the quantity of those elements that are present within the top 1-12 nm of the sample surface
  
  BULLET::::- What contamination, if any, exists on the surface or in the bulk of the sample
  
  BULLET::::- Empirical formula of a material that is free of excessive surface contamination
  
  BULLET::::- The chemical state identification of one or more of the elements in the sample and also give information on local bonding of atoms
  
  BULLET::::- The binding energy of one or more electronic states
   Colonel Goddard was the key forensic expert in solving the 1929 St. Valentine's Day Massacre in which seven gangsters were killed by rival Al Capone mobsters dressed as Chicago police officers. It also led to the establishment of the United States' first independent criminological laboratory, which was located at Northwestern University and headed by Goddard. At this new lab, ballistics, fingerprinting, blood analysis and trace evidence were all brought under one roof.
   Section::::Career and research.:Isotopes and mass spectrometry.
   Where:
  
  BULLET::::- "w": weight of internal standard
  
  BULLET::::- "w": weight of sample
  
  BULLET::::- "n"[H]: the integrated area of the peak selected for comparison in the standard, corrected for the number of protons in that functional group
  
  BULLET::::- "n"[H]: the integrated area of the peak selected for comparison in the sample, corrected for the number of protons in that functional group
  
  BULLET::::- "MW": molecular weight of standard
  
  BULLET::::- "MW": molecular weight of sample
  
  BULLET::::- "P": purity of internal standard
  
  Section::::Applications.:Non-destructive testing.
   Section::::Stable isotope labeling.:Isotope labeling measuring techniques.
  
  Any technique in measuring the difference between isotopomers can be used. The two primary methods, nuclear magnetic resonance (NMR) and mass spectrometry (MS), have been developed for measuring mass isotopomers in stable isotope labeling.
  