Ionizing radiation is radiation that has enough energy per particle to rip electrons off of atoms and therefore break chemical bonds. In contrast, radiation types such as microwaves, radio waves, and visible light are non-ionizing, meaning that they do not have enough energy to permanently damage molecules beyond simple heating effects.
Ionizing radiation includes X-rays, gamma rays, neutron radiation, proton radiation, and high-speed electrons. Natural sources of ionizing radiation include the radioactive decay of unstable atoms that exist everywhere and cosmic rays from space. Man-made sources include medical scans such as X-ray images as well as nuclear power plants, nuclear weapons testing, and any industrial or scientific process that involves nuclear reactions or high energies.
Advocating that humans cease all nuclear activity in order that our exposure to ionizing radiation will be reduced to zero makes no sense since we will always be exposed to some amount of ionizing radiation from natural sources.
The more logical approach is to allow nuclear research and technology to proceed, but put strong regulations and safety procedures in place so that humans are never exposed to ionizing radiation amounts that are above the safety threshold. The amount of total harm that ionizing radiation can cause a human depends on the total amount of radiation received, which is a function of the intensity of the radiation and the length of time that the person is exposed to the radiation.
The total amount of ionizing radiation received by a body is termed the "dose". Since different tissues react differently to ionizing radiation, of more importance is the "effective dose", which is the total amount of ionizing radiation received that is able to do biological damage. A person that is exposed to higher-than-normal levels of radiation, but only for limited amounts of time, will not receive a significantly higher effective dose and thus may still be in the safe zone.
For instance, employees can safely work in nuclear reactor facilities as long as they monitor their radiation exposure and limit their time in the facilities so that their dose does not exceed safe levels. For this reason a means of purification is often employed to inject a homogeneous sample into the capillary needle. High performance liquid chromatography , Capillary Electrophoresis , and Liquid-Solid Column Chromatography are methods of choice for this purpose.
The chosen purification method is then attached to the capillary needle, and the sample can be introduced directly. There are some clear advantages to using electrospray ionization mass spectrometry as an analytical method. One advantage is its ability to handle samples that have large masses. Another advantage is that this ionization method is one of the softest ionization methods available, therefore it has the ability to analyze biological samples that are defined by non-covalent interactions.
A quadrupole mass analyzer can also be used for this method, which means that a sample's structure can be determined fairly easily. Finally, the sensitivity for this instrument is impressive and therefore can be useful in accurate quantitative and qualitative measurements. Some disadvantages to electrospray ionization mass spectrometry are present as well. A major disadvantage is that this technique cannot analyze mixtures very well, and when forced to do so, the results are unreliable.
The apparatus is also very difficult to clean and has a tendency to become overly contaminated with residues from previous experiments. Finally, the multiple charges that are attached to the molecular ions can make for confusing spectral data. This confusion is further fueled by use of a mixed sample, which is yet another reason why mixtures should be avoided when using an electrospray ionization mass spectrometer.
The capillary needle is the inlet into the apparatus for the liquid sample. Once in the capillary needle, the liquid sample is nebulized and charged. There is a large amount of pressure being applied to the capillary needle, which in effect nebulizes the liquid sample forming a mist. The stainless steel capillary needle is also surrounded by an electrode that retains a steady voltage of around volts. This applied voltage will place a charge on the droplets.
Therefore, the mist that is ejected from the needle will be comprised of charged molecular ions. The molecular ions are oxidized upon entering the desolvating capillary, and a continual voltage is applied to the gas chamber in which this capillary is located. Here the desolvation process begins, through the use of a dry gas or heat, and the desolvation process continues through various pumping stages as the molecular ion travels towards the mass analyzer. An example of a dry gas would be an N 2 gas that has been dehydrated.
The gas or heat then provides means of evaporation, or desolvation, for the ionized droplets. As the droplets become smaller in size, their electric field densities become more concentrated. The increase in electric field density causes the like charges to repel one another, which induces an increase in surface tension.
The point where the droplet can no longer support this increase in surface tension is known as the Rayleigh limit. At this point, the droplet divides into smaller droplets of either positive or negative chrage. Ionisation If the number of electrons is equal to the number of protons then the atom is uncharged and is electrically neutral.
Example Carbon atom with six neutrons, six protons and six electrons If the atom is hit by an ionising radiation , it may lose an electron. Carbon ion with six neutrons, six protons and five electrons. National 5 Subjects National 5 Subjects up.
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