Semitone

H-alpha Emission: In the simplified Rutherford Bohr model of the hydrogen atom, the Balmer lines result from an electron jump between the second energy level closest to the nucleus, and those levels more distant. The $\scriptstyle 3\rightarrow 2$ transition depicted here produces an H-alpha photon, and the first line of the Balmer series. For hydrogen ($Z=1$) this transition results in a photon of wavelength 656 nm (red).

H-alpha (Hα) is a specific red visible spectral line in the Balmer series created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level. It is difficult for humans to see H-alpha at night, but due to the abundance of hydrogen in space, H-alpha is often the brightest wavelength of visible light in stellar astronomy.

Balmer series

According to the Bohr model of the atom, electrons exist in quantized energy levels surrounding the atom's nucleus. These energy levels are described by the principal quantum number n = 1, 2, 3, ... . Electrons may only exist in these states, and may only transit between these states.

The set of transitions from n ≥ 3 to n = 2 is called the Balmer series and its members are named sequentially by Greek letters:

• n = 3 to n = 2 is called Balmer-alpha or H-alpha,
• n = 4 to n = 2 is called Balmer-beta or H-beta,
• n = 5 to n = 2 is called Balmer-gamma or H-gamma, etc.

For the Lyman series the naming convention is:

• n = 2 to n = 1 is called Lyman-alpha,
• n = 3 to n = 1 is called Lyman-beta, etc.

H-alpha has a wavelength of 656.281 nm, is visible in the red part of the electromagnetic spectrum, and is the easiest way for astronomers to trace the ionized hydrogen content of gas clouds. Since it takes nearly as much energy to excite the hydrogen atom's electron from n = 1 to n = 3 as it does to ionize the hydrogen atom, the probability of the electron being excited to n = 3 without being removed from the atom is very small. Instead, after being ionized, the electron and proton recombine to form a new hydrogen atom. In the new atom, the electron may begin in any energy level, and subsequently cascades to the ground state (n = 1), emitting photons with each transition. Approximately half the time, this cascade will include the n = 3 to n = 2 transition and the atom will emit H-alpha light. Therefore, the H-alpha line occurs where hydrogen is being ionized.

The H-alpha line saturates (self-absorbs) relatively easily because hydrogen is the primary component of nebulae, so while it can indicate the shape and extent of the cloud, it cannot be used to accurately determine the cloud's mass. Instead, molecules such as carbon dioxide, carbon monoxide, formaldehyde, ammonia, or acetonitrile are typically used to determine the mass of a cloud.

The four visible hydrogen emission spectrum lines in the Balmer series. The red line at far-right is H-alpha

Singapore was ranked 11 th out of sixty six cities in a 2012 International Cities Index rating on leaders in globalisation URA). In contrast, when adjusted for inflation, the property value index really fell by round 1.1% over the identical interval. In 2011, consumers from China had been the most important group of foreign property patrons in Singapore. (Yahoo! file photograph) Welcome to Singapore Property For Sale! That includes Singapore, JB Iskandar, London, Australia, Philipiines, Cambodia Property!

David Drabek has me concerned. he replied to considered one of my postings that included a bit of furnishings on the market. We first talked by way of electronic mail. He informed me approx the place he lives which would be approx 12 miles from my home. Then we were tlking over the telephone a number of instances as to what day he could come. He gave me an approx date. Supposedly because of his work schedule. Since the day we mentioned a day I have not heard any response. I have left messages on each telephone and email. If he modified his thoughts why not just reply the telephone or e-mail and tell me. Now I am attempting to determine the e-mail tackle he was utilizing. I discovered the companyand can contact them to see what they could or could not know.

One other major development concerning concurrent HDB ownership concerns private property owners who are actually successfully banned from buying HDB resale flats for investment purposes. HDB has carried out a new rule requiring non-public property owners who purchase a HDB flat to dispose of their non-public property inside six months. Similarly, buyers of HDB flats who didn't obtain any subsidies may not purchase personal property throughout the minimum occupation interval (MOP), which has now been extended from three to 5 years. Other than prolonging the "upgrading" cycle, these new restrictions will considerably impression funding demand, significantly in the non-public housing sector. Extension of Holding Interval on Seller's Stamp Duty

An exquisite assortment of particular person type flats which have just lately been refurbished to a really excessive normal, offering very spacious lodging. Nicely geared up full kitchen, together with a washer - dryer. -Conveniently Located-Each day Cleaning To start with, I did not realise that they are scammers as I would like a room so bad, but when I received their replies with comparable data that every one of them are at present in London, I suspect there was one thing unsuitable here. Particularly when I negotiated, they directly accredited it. Lastly I searched the addresses of the residences they offered and I discovered the images and the costs are completely totally different from the Area.com.au. LOCATION OF THE CONDOMINIUM Utilizing my accounts you'll be able to submit in multiple cities.

How are you doing at this time? I have enclosed pictures of my condo within the attached under and do get again to me asap if you're nonetheless concerned about renting residence or not. Wanting ahead to hear from you. Apartments is Situated in the course of the city. Reverse Rundell Mall tram cease, and opposite Rundell Mall itself. quarter-hour stroll to UniSA Metropolis West and Metropolis East campus, Uni Adelaide, UNITECH and Chinatown. At first, thanks for your interest within the residence. I'm out there to indicate the home this week if that matches your schedule. Just to give you a little more information about the house, the water, trash and rubbish are paid by us. The security deposit might be paid in 2 installments if cash is tight. (I understand how that can be).

One factor we've got on this country is a big group of "economists," and "market analysts." What's interesting about this group of real property market-watchers is that there are two very different ways through which they predict Boomers will influence housing markets over the next decade. Let's check out those two opposites and see how each can change the way in which real property buyers method their markets. Quiet Enjoyment 19. The Landlord covenants that on paying the Hire and performing the covenants contained in this Settlement, the Tenant will peacefully and quietly have, hold, and benefit from the Property for the agreed time period. Register now for VIP preview quickly this Might and be the 1st toselect your selection unit at particular Preview Worth. No overseas income tax

The place you might be shopping for property which is underneath building, the Singapore Academyof Law will hold a portion of the acquisition monies as stakeholders until the expiryof the defects legal responsibility interval offered in the Agreement/Contract. GST just isn't payable on residential property at present. However, as some residentialproperties (e.g. shophouse with a flat above) might contain a industrial componentyou should seek advice from your lawyer on this. Your Lawyer's Role in a Property Sale Singapore residents shopping for their second homes will likely be hit with an ABSD of seven% whereas people with permanent residency status will pay an additional stamp duty of 5% on their first dwelling purchase. For extra information and analysis on Singapore Price range 2013, click on here for ST's Massive Story coverage.

It is because the variety of new properties in singapore; additional resources, cluster-housing launches appears to be like set to fall after this yr, following a current change in Authorities regulations, say property specialists. Analysts noted that cluster homes are widespread among larger families, preferring the bigger constructed-up space typical of landed homes however want to have apartment amenities as well. Merely simply name me or fill up my Promoting / Leasing Enquiry type when you're able to put up your property in the marketplace.Your property will obtain its own internet page which includes full property data and pictures, hyperlinks to maps, community info. Deborah Legislation from Expat Realtor shares her property market update, plus prime rental flats and houses at the moment available to lease Student's boarding house or hostel

Filter

The Sun observed through a telescope with an H-alpha filter

Milky Way view by Wisconsin H-Alpha Mapper survey

Amateur image of NGC 6888 using H-alpha (3nm) filter.

A hydrogen-alpha filter is an optical filter designed to transmit a narrow bandwidth of light generally centered on the H-alpha wavelength. They are characterized by a bandpass width that measures the width of the wavelength band that is transmitted. These filters are manufactured by multiple (~50) vacuum-deposited layers. These layers are selected to produce interference effects that filter out any wavelengths except at the requisite band.

Alternatively, an etalon may be used as the narrow band filter (in conjunction with a "blocking filter" or energy rejection filter) to pass only a narrow (<0.1 nm) range of wavelengths of light centered around the H-alpha emission line. The physics of the etalon and the dichroic interference filters are essentially the same (relying on constructive/destructive interference of light reflecting between surfaces), but the implementation is different (an interference filter relies on the interference of internal reflections). Due to the high velocities sometimes associated with features visible in H-alpha light (such as fast moving prominences and ejections), solar H-alpha etalons can often be tuned (by tilting or changing the temperature) to cope with the associated Doppler effect.

See also

• Hydrogen spectral series
• Rydberg formula