INTERPRETING LINES IN THE SPECTROSCOPE

1
INTERPRETING LINES IN THE SPECTROSCOPE

• Geo 240
• D. B. McKinney

2
Indexing the Films

• The electrodes contain Na, thus the sodium
  doublet lines are always present and provide an
  internal calibration or indexing mark.

3

• In this example the Angstrom scale film is
  correctly indexed, the Ca film is not. To index
  the Ca film, you would adjust the film cranks to
  bring the index lines on the film (usually right
  below element symbol) into alignment with the Na
  doublet in the spectra (center).

4

• . Here, the Ca film has been adjusted so that it
  is now correctly indexed. Note the diagonal
  arrow marking the Na doublet lines on the Ca
  film, that they are now aligned with the Na
  doublet lines in the spectra.

5
Using Key Line Film
Watch for flashing lines as sample is
raised/lowered. Then investigate films for
elements with those lines.
OUT
6
Using Key Line Film
Watch for flashing lines as sample is
raised/lowered. Then investigate films for
elements with those lines.
IN
7
Using Key Line Film
Watch for flashing lines as sample is
raised/lowered. Then investigate films for
elements with those lines.
OUT
8
Using Key Line Film
Watch for flashing lines as sample is
raised/lowered. Then investigate films for
elements with those lines.
IN
9
Using Key Line Film
Watch for flashing lines as sample is
raised/lowered. Then investigate films for
elements with those lines.
OUT
10
Using Key Line Film
Watch for flashing lines as sample is
raised/lowered. Then investigate films for
elements with those lines.
IN
11

• In the example shown, there appear to be lines
  for Li and Sn. Treating those as hypotheses,
  you would then dial up the films for those
  elements and compare each to the observed
  pattern.
• Key lines give you a guess that you must confirm
  with the full spectral pattern.

12
Following up
Element name and film number, Na doublet lines
marked with diagonal arrow.

• The Li Film, 45

Heavy arrowLine of Max Sensitivity. If another
element appears, it is an element that has a
similar line, might be misidentified for this
line. Check that film too!