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Ultravoilet (UV) Light Spectrum of flourescent lamps
1Abd Rahman Tamuri*, 1Muhamad Assyafiq Sahar, 1Noor Sarah Akmal Abu Bakar, 2Mohd
Nizam Lani, 1Moses Elisha Kundel and 1Yaacob Mat Daud
1 Physics Department, Faculty of Science, UTM JB 81310 Johor Bharu, Johor, Malaysia
2 School of Food Science and Technology, Universiti Malaysia Terengganu, 21030 Kuala
Terengganu, Terengganu, Malaysia
Abstract
Ultraviolet light is the electromagnectic radiation in
the range of 100 nm to 400 nm. The UV light
spectrum consists of electromagnetic waves with
frequencies higher than those that humans can
identify as the violet in colour. These frequencies
are invisible to most humans except those with
aphakia (the absence of the lens of the eye). There
are two sources of UV light; natural and artifical
sources. The sunlight is the main source of the
natural UV ligth. On the other hand, the artifical
source could be generated by florescent lamp, gas-
discharge lamp, laser, and LED. In this paper, the
spectrum of the common ultraviolet light in the
market such as the black light lamp, germicidal
lamp, aquarium lamp and insect lamp will be
discussed. The spectrum of UV light for each lamp
was placed in a box of 10x12x12 cm and detected
by a special spectrometer that directly connected to
a computer via USB connection. The result shows
that the main spectral lines of all fluorescent lamps
are 254 nm, 313 nm, 404 nm, 437 nm, and 546 nm.
The information of the various spectrums of the UV
lamp is very important for the user. This
information can be used to prevent over exposure of
UV lights to humans that may potentially cause
skin cancer.
1. INTRODUCTION
The complete electromagnectic energy
spectrum of natural sunlight normally divided into
ultraviolet light, visible light and infrared light
(Brennan, Fedor et al. 1988). Ultraviolet light is the
electromagnetic spectrum with the wavelengths in
the range of 100 and 400 nm. The ultraviolet
spectrum further subdivides into UVA, UVB and
UVC (Brennan, Fedor et al. 1988; Koutchma,
Forney et al. 2010) as shown in Table 1.
TABLE 1. Ultraviolet types.
Electromagnetic energy at a particular wavelength,
λ has an associated frequency, v and photon energy
E. They are related according to the equations: λ =
c/v and
(1)
where c; speed of light is 299792458 m/s and h is
Planck’s constant (6.6261 x 10-34 Js). Across the
electromagnetic spectrum, there exists an extremely
wide range of wavelengths and corresponding
photon energies.
2. FUNDAMENTAL OF FLUORESCENT
LAMPS
The UV light also could be generated by
artificial technique use of fluorescent UV lamps.
Usually a fluorescent lamp is filled with a low
pressure mercury-vapor and mix of noble gas such
as Argon, Xenon, Krypton and Neon (Koutchma,
Forney et al. 2010). The inner surface of the tube is
coated with a fluorescent material. The electrodes
of tube are typically made of coiled tungsten to
emit electrons and also coated with a mixture of
Barium, Strontium and Calcium Oxides chosen to
have a low thermoionic emission temperature (Jin,
Liu et al. 2007).
Name
Abbreviation
Wavelength,
nm
Energy per
photon,eV
Ultraviolet A
Ultraviolet B
Ultraviolet C
UVA
UVB
UVC
400 - 315
315 - 280
280 - 100
3.10 – 3.94
3.94 – 4.43
4.43 – 12.4
When an electrical current is supplied to
the fluorescent tube, the electrodes will emit free
electrons. Then, these free electrons will have
enough kinetic energy to collide with the gas
mixture inside the tube. Which then, it will transfers
the energy to the outer electrons of the atoms in the
gas mixture and turn them into temporarily excited
state. At a higher energy state is unstable, then the
atoms will emit short-wave ultravoilet radiation.
The electrons of the atoms reverts to a lower state
and become more stable. Most of the photons that
are released from the Mercury atoms have
wavelengths in the ultraviolet (UV) region of the
spectrum, predominantly at wavelengths of 253.7
nm (Hatch and Ott 1968).
This wavelength is not visible to human
eyes. However it could be converted into visible
light by using of phosphor material. The UV
photons are absorbed by electrons of atoms of the
coated phosphor in the tube, causing a similar
energy jump, then drop, with emission of a further
photon. The emitted photons from the second
interaction have a lower energy than the previous
one. The chemicals of phosphor was chosen so that
these emitted photons becomes visible to the human
eye. The difference of energy between the absorbed
ultra-violet photon and the emitted visible light
photon goes toward heating up the phosphor
coating.
Phosphors are substances that give off
light when they are exposed to light. Manufacturers
can vary the color of the light by using different
combinations of phosphors. For example, the
blacklight lamps provide near UV light of 360 nm
are usually used the materials from Wood’s glass
that contained the Europium-doped strontium
fluoroborate (Sakamoto, Kousaka et al. 2011).
Furthermore, UVB phosphors had the general
formula (LaGdY)PO4:Cez was invented to produce
the UVB light with a range of wavelength between
280 nm to 320 nm (Justel, Mayr et al. 2012).
However, if no phosphor was coated at all, the tube
become germicidal lamp. Usually the tube was
made from fuses quartz that is transparent to the
UV light. The main property of germicidal lamp is
the 254 nm that are effective for destruction of most
microorganisms (Kowalski 2009; Miller, Linnes et
al. 2013).
3. EXPERIMENT
Figure 1 shows the experimental setup for
this experiment. Four type fluorescent lamps
include 10 W Reno blacklight lamp, 10 W Sonic
aquarium lamp, 10 W Senkyo germicidal lamp and
10 W Hitachi insect lamp were placed in a box of
10x12x12 cm. A fibre optic connector was placed
in a small hole at the top of the box. A compact
LR1 spectrometer with range of 200 nm to 1200 nm
and resolution of 1 nm were used to detect the
radiation from the fluorescent lamps.
Figure 1: The experimental setup of Flourescent
UV lamps
With the aid of CCD camera and electronic
components, a serial data was sent to the computer
via USB connection. The data was interfaced by
using a LRI software and was replotted by using
software GnuPlot version 4.6.
4. RESULTS AND DISCUSSION
Figure 2 shows the sunlight spectrum
detected by LR1 spectrometer in Kuala
Terengganu, Malaysia at 10 AM. The visible light
is defined as radiation between 400 to 760 nm and
UV light consist of radiation below 400 nm. As
shown in the Figure 2, the UVC was not appeared
in our sunlight spectrum, but only UVA and UVB
were appeared. The UVC from the sunlight was
absorbed by the ozone. Only the small portion of
UV in sunlight is important to cause damage of
plastics, textiles, paints and the skin cancer
(Brennan, Fedor et al. 1988).
Figure 2: The sunlight spectrum at Kuala
Terengganu at 10 AM.
However, the Figure 3(a), 3(b), 3(c) and
3(d) show the artificial UV fluorescent lamp
spectrums for 10 W Sonic Aquarium, 10 W Reno
Blacklight, 10 W Hitachi Insect and 10 W Senkyo
Germicidal lamp respectively. The main spectral
line of all fluorescent lamps are 254 nm, 313 nm,
Compact LR1 Spectrometer
Flourescent UV Lamp
USB Connection
Fibre optics connection
10x12x12 cm box
404 nm, 437 nm, and 546 nm. These results have a
good agreement with spectral lines of Mercury
(Sansonetti, Salit et al. 1996).
Figure 3(a): Sonic aquarium lamp, look similar to
the sunlight spectrum.
Figure 3(a) shows the commercial Sonic
aquarium lamp. The spectrum are mixture of red,
green and blue phosphors, the red phosphor
emitting predominantly in the spectral region of
from 610 nm to 620 nm, the green phosphor
emitting predominantly in the spectral region of
from 540 nm to 545 nm and the blue phosphor
having a peak emission wavelength between 430
nm and 480 nm (Abeywickrama and Newman
1991). Aquarium lamp is suitable to aquatic life of
fish and the UVA (366 nm) could be used to kill the
pathogenic bacteria in water (Wegelin, Canonica et
al. 1994).
Figure 3(b) and Figure 3(c) show the Reno
Blacklight lamp and Hitachi Insect lamp,
respectively. Both lamps show the same pattern of
spectrum. However, there was a small amount of
spectral line of 546 nm for Hitachi Insect lamp.
Most of the insects are often attracted to the range
of wavelength. Light traps for forecasting pest
outbreaks, and electric insect killers are devices that
have been developed based on understanding the
nature of behaviour of insects towards this
particular wavelength (Shimoda and Honda 2013).
Figure 3(b): Reno Blacklight lamp
The 10 W Senkyo germicidal lamp
spectrum is purely consisted of low pressure
Mercury vapor flourescent lamp without any coated
phoshpor. The spectrum lines of this lamp are the
same spectrum lines are emitted by Mercury
(Sansonetti, Salit et al. 1996). The germicidal lamp
is usually used to kill all the microorganisms that
present in air or water. The main wavelength of
germicidal lamp is 254 nm that could penetrate the
DNA structure of microbial cells that will modify
their DNA and cause severe damage (Florea,
BrĂTucu et al. 2012; Miller, Linnes et al. 2013).
Figure 3(c): Hitachi Insect lamp, dominant
wavelenght at 360 nm (UVB)
Figure 3(d): A germicidal lamp, without the
phosphor coating. The main spectral line Mercury-
vapor are at 254 nm, 313 nm, 404 nm, 437 nm, and
546 nm.
Figure 4: The combination of spectrums of all
fluorescent lamps in this experiment
Figure 4 shows graph of the combination
of all spectrum of fluorescent lamps in this
experiment compare to the natural sunlight. The
natural sunlight consist of the all visible light (400
nm to 760 nm) and UV light (below 400 nm). The
artifical UV fluorescent lamp mainly emitted by
low pressure Mercury vapor have several main
wavelength such as 254 nm, 313 nm, 404 nm, 437
nm, and 546 nm. The phosphor materials absorb the
UV light and convert into the visible light. The
information of each spectrum is very important that
could help the user to know the safety precaution,
especially steps to avoid skin cancer.
5. CONCLUSION
In conclusion, the fluorescent lamps were
designed based on low pressure Mercury vapor.
The main emitted wavelength were 254 nm, 313
nm, 404 nm, 437 nm, and 546 nm. The phosphor
materials used had absorbed the UV light and
converted into visible light. Germicidal lamp is
very useful to kill harmful and pathogenic
microorganisms to human. The information of the
various spectrums of the UV fluorescent lamp is
very important for the user that could prevent the
over exposure to the human skin that could
potentially cause skin cancer.
6. ACKNOWLEDGEMENTS
The authors thank to Universiti Teknologi Malaysia
and Goverment of Malaysia for financial supported
for this project through Geran Universiti
Penyelidikan (GUP) Q.J130000.2626.07J56.
7. REFERENCES
Abeywickrama, M. G. and B. J. Newman (1991).
Fluorescent lamp for use in aquaria,
Google Patents.
Brennan, P., C. Fedor, et al. (1988). "Sunlight, UV
and accelerated weathering." Paint and
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light for disinfecting the water used in
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Hatch, W. R. and W. L. Ott (1968). "Determination
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emission from functionalized carbon
nanotubes with a barium strontium oxide
coating produced by magnetron
sputtering." Carbon 45(3): 587-593.
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having a UVB phosphor, Google Patents.
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principles and applications, CRC Press.
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Berlin Heidelberg.
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germicidal irradiation: future directions for
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Abd Rahman Tamuri received the First
Class B.Sc (2005), and Ph.D (2009)
degrees from Universiti Teknologi
Malaysia. He is a Senior Lecturer in in
Physics Department, Faculty of Science,
Universiti Teknologi Malaysia. His current
interest include of high power UV laser,
Java programming for computer
interfacing and laser physics.
Yaacob Mat Daud received the B.Sc Hon
(1980) from Universiti Kebangsaan
Malaysia, M.Sc (1983) and Ph.D (1990) in
University of Kent. He is currently a Ascc.
Prof in Physics Department, Universiti
Teknologi Malaysia. His current interests
include computer interfacing, electronic
controller, laser system
Mohd Nizam Lani received B.Sc (1999)
and M.Sc (2003) from Universiti Putra
Malaysia and PhD (2007) from University
Strathclyde, UK. His is a Senior Lecturer
in School of Food Science and
Technology, Universiti Malaysia
Terengganu. His current research on food
microbiology, food safety and pulsed UV
light system.
Moses Elisha Kundwal is currently a PhD
student at Physics Department, Universiti
Teknologi Malaysia. His current project is
to study the effectiveness of UV laser to
micro-organisms.
Mohamad Assyafiq Sahar is current a
final year student in Physics Department,
Universiti Teknologi Malaysia. His current
interest is electronic and instrumentation
Noor Sarah Akmal Abu Bakar is a final
year student in Physics Department,
Universiti Teknologi Malaysia.