The rotation of the orientation of linearly
polarized light was first observed in 1811 in
quartz by French physicist François Jean
Dominique Arago. In 1822, the English
astronomer Sir John F.W. Herschel discovered
that different individual quartz crystals, whose
crystalline structures are mirror images of each
other (see illustration), rotate linear polarization
by equal amounts but in opposite directions.
Jean Baptiste Biot also observed the rotation of
the axis of polarization in certain liquids and
gases[ citation needed ] of organic substances
such as turpentine. Simple polarimeters have
been used since this time to measure the
concentrations of simple sugars, such as
glucose , in solution. In fact one name for D-
glucose (the biological isomer), is dextrose ,
referring to the fact that it causes linearly
polarized light to rotate to the right or dexter
side. In a similar manner, levulose, more
commonly known as fructose, causes the plane
of polarization to rotate to the left. Fructose is
even more strongly levorotatory than glucose is
dextrorotatory. Invert sugar syrup , commercially
formed by the hydrolysis of sucrose syrup to a
mixture of the component simple sugars,
fructose, and glucose, gets its name from the
fact that the conversion causes the direction of
rotation to "invert" from right to left.
In 1849, Louis Pasteur resolved a problem
concerning the nature of tartaric acid . A
solution of this compound derived from living
things (to be specific, wine lees) rotates the
plane of polarization of light passing through it,
but tartaric acid derived by chemical synthesis
has no such effect, even though its reactions
are identical and its elemental composition is
the same. Pasteur noticed that the crystals
come in two asymmetric forms that are mirror
images of one another. Sorting the crystals by
hand gave two forms of the compound:
Solutions of one form rotate polarized light
clockwise, while the other form rotate light
counterclockwise. An equal mix of the two has
no polarizing effect on light. Pasteur deduced
that the molecule in question is asymmetric and
could exist in two different forms that resemble
one another as would left- and right-hand
gloves, and that the organic form of the
compound consists of purely the one type.
polarized light was first observed in 1811 in
quartz by French physicist François Jean
Dominique Arago. In 1822, the English
astronomer Sir John F.W. Herschel discovered
that different individual quartz crystals, whose
crystalline structures are mirror images of each
other (see illustration), rotate linear polarization
by equal amounts but in opposite directions.
Jean Baptiste Biot also observed the rotation of
the axis of polarization in certain liquids and
gases[ citation needed ] of organic substances
such as turpentine. Simple polarimeters have
been used since this time to measure the
concentrations of simple sugars, such as
glucose , in solution. In fact one name for D-
glucose (the biological isomer), is dextrose ,
referring to the fact that it causes linearly
polarized light to rotate to the right or dexter
side. In a similar manner, levulose, more
commonly known as fructose, causes the plane
of polarization to rotate to the left. Fructose is
even more strongly levorotatory than glucose is
dextrorotatory. Invert sugar syrup , commercially
formed by the hydrolysis of sucrose syrup to a
mixture of the component simple sugars,
fructose, and glucose, gets its name from the
fact that the conversion causes the direction of
rotation to "invert" from right to left.
In 1849, Louis Pasteur resolved a problem
concerning the nature of tartaric acid . A
solution of this compound derived from living
things (to be specific, wine lees) rotates the
plane of polarization of light passing through it,
but tartaric acid derived by chemical synthesis
has no such effect, even though its reactions
are identical and its elemental composition is
the same. Pasteur noticed that the crystals
come in two asymmetric forms that are mirror
images of one another. Sorting the crystals by
hand gave two forms of the compound:
Solutions of one form rotate polarized light
clockwise, while the other form rotate light
counterclockwise. An equal mix of the two has
no polarizing effect on light. Pasteur deduced
that the molecule in question is asymmetric and
could exist in two different forms that resemble
one another as would left- and right-hand
gloves, and that the organic form of the
compound consists of purely the one type.
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